Add Plugin Contributor (#1387)

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**- Summary**
Add Plugin Contributor https://github.com/hennessyevan/netlify-cms-widget-youtube
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**- Test plan**

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![image](https://user-images.githubusercontent.com/16711653/40568474-bfb40350-6048-11e8-8d2e-3465cb8d8ba0.png)

.all-contributorsrc

@@ -937,6 +937,15 @@
       "contributions": [
         "code"
       ]
+    },
+    {
+      "login": "hennessyevan",
+      "name": "Evan Hennessy",
+      "avatar_url": "https://avatars1.githubusercontent.com/u/16711653?v=4",
+      "profile": "https://www.hennessyevan.com",
+      "contributions": [
+        "plugin"
+      ]
     }
   ]
 }

README.md

@@ -1,5 +1,5 @@
 # Netlify CMS
-[![All Contributors](https://img.shields.io/badge/all_contributors-107-orange.svg)](#contributors)
+[![All Contributors](https://img.shields.io/badge/all_contributors-108-orange.svg)](#contributors)
 [![Open Source Helpers](https://www.codetriage.com/netlify/netlify-cms/badges/users.svg)](https://www.codetriage.com/netlify/netlify-cms)
 [![](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/netlify/netlifycms)
 
@@ -60,7 +60,6 @@ These services support Netlify CMS development by providing free infrastructure.
 These wonderful folks are responsible for developing and maintaining Netlify CMS. ([emoji key](https://github.com/kentcdodds/all-contributors#emoji-key))
 
 <!-- ALL-CONTRIBUTORS-LIST:START - Do not remove or modify this section -->
-<!-- prettier-ignore -->
 | [<img src="https://avatars2.githubusercontent.com/u/33676?v=4" width="100px;"/><br /><sub><b>Cássio Souza</b></sub>](https://twitter.com/cassiozen)<br />[💻](https://github.com/netlify/netlify-cms/commits?author=cassiozen "Code") | [<img src="https://avatars3.githubusercontent.com/u/2112202?v=4" width="100px;"/><br /><sub><b>Shawn Erquhart</b></sub>](https://erquh.art)<br />[💻](https://github.com/netlify/netlify-cms/commits?author=erquhart "Code") | [<img src="https://avatars3.githubusercontent.com/u/11071?v=4" width="100px;"/><br /><sub><b>Andrey Okonetchnikov</b></sub>](http://okonet.ru)<br />[💻](https://github.com/netlify/netlify-cms/commits?author=okonet "Code") | [<img src="https://avatars0.githubusercontent.com/u/6515?v=4" width="100px;"/><br /><sub><b>Mathias Biilmann</b></sub>](https://www.netlify.com)<br />[💻](https://github.com/netlify/netlify-cms/commits?author=biilmann "Code") | [<img src="https://avatars1.githubusercontent.com/u/1425133?v=4" width="100px;"/><br /><sub><b>Benaiah Mischenko</b></sub>](http://benaiah.me)<br />[💻](https://github.com/netlify/netlify-cms/commits?author=Benaiah "Code") | [<img src="https://avatars0.githubusercontent.com/u/2281080?v=4" width="100px;"/><br /><sub><b>Rafael Conde</b></sub>](http://rafaelconde.net)<br />[🎨](#design-rafaelconde "Design") [💻](https://github.com/netlify/netlify-cms/commits?author=rafaelconde "Code") | [<img src="https://avatars0.githubusercontent.com/u/2513147?v=4" width="100px;"/><br /><sub><b>Joseph Earl</b></sub>](http://josephearl.co.uk)<br />[💻](https://github.com/netlify/netlify-cms/commits?author=josephearl "Code") |
 | :---: | :---: | :---: | :---: | :---: | :---: | :---: |
 | [<img src="https://avatars2.githubusercontent.com/u/5713670?v=4" width="100px;"/><br /><sub><b>Brian Douglas</b></sub>](https://briandouglas.me/)<br />[💻](https://github.com/netlify/netlify-cms/commits?author=bdougie "Code") | [<img src="https://avatars3.githubusercontent.com/u/44568?v=4" width="100px;"/><br /><sub><b>Frances Berriman</b></sub>](https://fberriman.com)<br />[🎨](#design-phae "Design") | [<img src="https://avatars0.githubusercontent.com/u/1050?v=4" width="100px;"/><br /><sub><b>David Calavera</b></sub>](https://github.com/calavera)<br />[💻](https://github.com/netlify/netlify-cms/commits?author=calavera "Code") | [<img src="https://avatars0.githubusercontent.com/u/8883545?v=4" width="100px;"/><br /><sub><b>Luis Correia</b></sub>](https://luisc.pt)<br />[💻](https://github.com/netlify/netlify-cms/commits?author=lmcorreia "Code") | [<img src="https://avatars1.githubusercontent.com/u/20345941?v=4" width="100px;"/><br /><sub><b>Caleb</b></sub>](https://github.com/tech4him1)<br />[💻](https://github.com/netlify/netlify-cms/commits?author=tech4him1 "Code") | [<img src="https://avatars0.githubusercontent.com/u/3292160?v=4" width="100px;"/><br /><sub><b>Jerry Holmes</b></sub>](http://www.pagedragon.com)<br />[💻](https://github.com/netlify/netlify-cms/commits?author=jholmes033169 "Code") | [<img src="https://avatars0.githubusercontent.com/u/8377185?v=4" width="100px;"/><br /><sub><b>abumalick</b></sub>](https://github.com/abumalick)<br />[💻](https://github.com/netlify/netlify-cms/commits?author=abumalick "Code") |
@@ -77,7 +76,7 @@ These wonderful folks are responsible for developing and maintaining Netlify CMS
 | [<img src="https://avatars2.githubusercontent.com/u/283419?v=4" width="100px;"/><br /><sub><b>Tim Carry</b></sub>](http://www.pixelastic.com/)<br />[💻](https://github.com/netlify/netlify-cms/commits?author=pixelastic "Code") [🎨](#design-pixelastic "Design") [📖](https://github.com/netlify/netlify-cms/commits?author=pixelastic "Documentation") | [<img src="https://avatars0.githubusercontent.com/u/30510616?v=4" width="100px;"/><br /><sub><b>Sol Park</b></sub>](https://github.com/solpark)<br />[💻](https://github.com/netlify/netlify-cms/commits?author=solpark "Code") | [<img src="https://avatars0.githubusercontent.com/u/29218846?v=4" width="100px;"/><br /><sub><b>Michael Romani</b></sub>](https://github.com/MichaelRomani)<br />[💻](https://github.com/netlify/netlify-cms/commits?author=MichaelRomani "Code") | [<img src="https://avatars1.githubusercontent.com/u/15175868?v=4" width="100px;"/><br /><sub><b>Xifeng Jin</b></sub>](http://linkedin/in/xifengjin88)<br />[🐛](https://github.com/netlify/netlify-cms/issues?q=author%3Axifengjin88 "Bug reports") [💻](https://github.com/netlify/netlify-cms/commits?author=xifengjin88 "Code") | [<img src="https://avatars1.githubusercontent.com/u/372831?v=4" width="100px;"/><br /><sub><b>Pedro Duarte</b></sub>](http://pedroduarte.me)<br />[🐛](https://github.com/netlify/netlify-cms/issues?q=author%3Apeduarte "Bug reports") [💻](https://github.com/netlify/netlify-cms/commits?author=peduarte "Code") [📖](https://github.com/netlify/netlify-cms/commits?author=peduarte "Documentation") | [<img src="https://avatars1.githubusercontent.com/u/6064830?v=4" width="100px;"/><br /><sub><b>Antonio Argote</b></sub>](http://antonioargote.com)<br />[🎨](#design-Strangehill "Design") | [<img src="https://avatars3.githubusercontent.com/u/1479451?v=4" width="100px;"/><br /><sub><b>Kristaps Taube</b></sub>](https://www.ktaube.com)<br />[💻](https://github.com/netlify/netlify-cms/commits?author=ktaube "Code") |
 | [<img src="https://avatars3.githubusercontent.com/u/26639499?v=4" width="100px;"/><br /><sub><b>David Ko</b></sub>](https://github.com/daveyko)<br />[💻](https://github.com/netlify/netlify-cms/commits?author=daveyko "Code") | [<img src="https://avatars3.githubusercontent.com/u/440562?v=4" width="100px;"/><br /><sub><b>Iñaki García</b></sub>](http://www.txorua.com)<br />[🎨](#design-igarbla "Design") | [<img src="https://avatars3.githubusercontent.com/u/27162255?v=4" width="100px;"/><br /><sub><b>Sam</b></sub>](https://github.com/gazebosx3)<br />[💻](https://github.com/netlify/netlify-cms/commits?author=gazebosx3 "Code") | [<img src="https://avatars1.githubusercontent.com/u/174777?v=4" width="100px;"/><br /><sub><b>Josh Dzielak</b></sub>](https://dzello.com)<br />[📖](https://github.com/netlify/netlify-cms/commits?author=dzello "Documentation") | [<img src="https://avatars0.githubusercontent.com/u/2193?v=4" width="100px;"/><br /><sub><b>Jeremy Bise</b></sub>](http://thosegeeks.com)<br />[📖](https://github.com/netlify/netlify-cms/commits?author=jeremybise "Documentation") | [<img src="https://avatars2.githubusercontent.com/u/13282103?v=4" width="100px;"/><br /><sub><b>terrierscript</b></sub>](https://terrierscript.com)<br />[💻](https://github.com/netlify/netlify-cms/commits?author=terrierscript "Code") | [<img src="https://avatars0.githubusercontent.com/u/3949335?v=4" width="100px;"/><br /><sub><b>Christopher Geary</b></sub>](https://twitter.com/crgeary)<br />[🔌](#plugin-crgeary "Plugin/utility libraries") |
 | [<img src="https://avatars0.githubusercontent.com/u/23248886?v=4" width="100px;"/><br /><sub><b>Brian Macdonald</b></sub>](https://github.com/brianlmacdonald)<br />[💻](https://github.com/netlify/netlify-cms/commits?author=brianlmacdonald "Code") | [<img src="https://avatars1.githubusercontent.com/u/15092?v=4" width="100px;"/><br /><sub><b>John Vandenberg</b></sub>](https://jayvdb.github.io/)<br />[📖](https://github.com/netlify/netlify-cms/commits?author=jayvdb "Documentation") | [<img src="https://avatars2.githubusercontent.com/u/24911956?v=4" width="100px;"/><br /><sub><b>MarkZither</b></sub>](https://github.com/MarkZither)<br />[📖](https://github.com/netlify/netlify-cms/commits?author=MarkZither "Documentation") | [<img src="https://avatars1.githubusercontent.com/u/9257284?v=4" width="100px;"/><br /><sub><b>Rob Phoenix</b></sub>](https://www.robphoenix.com)<br />[📖](https://github.com/netlify/netlify-cms/commits?author=robphoenix "Documentation") | [<img src="https://avatars2.githubusercontent.com/u/3028764?v=4" width="100px;"/><br /><sub><b>Steve Lathrop</b></sub>](https://www.SteLa.io)<br />[💻](https://github.com/netlify/netlify-cms/commits?author=slathrop "Code") [📖](https://github.com/netlify/netlify-cms/commits?author=slathrop "Documentation") [💡](#example-slathrop "Examples") | [<img src="https://avatars0.githubusercontent.com/u/10004167?v=4" width="100px;"/><br /><sub><b>Maciej Matuszewski</b></sub>](https://github.com/maciejmatu)<br />[💻](https://github.com/netlify/netlify-cms/commits?author=maciejmatu "Code") | [<img src="https://avatars0.githubusercontent.com/u/36023898?v=4" width="100px;"/><br /><sub><b>Eko Eryanto</b></sub>](https://github.com/ekoeryanto)<br />[🔌](#plugin-ekoeryanto "Plugin/utility libraries") |
-| [<img src="https://avatars3.githubusercontent.com/u/366688?v=4" width="100px;"/><br /><sub><b>Taylor D. Edmiston</b></sub>](http://blog.tedmiston.com/)<br />[📖](https://github.com/netlify/netlify-cms/commits?author=tedmiston "Documentation") | [<img src="https://avatars2.githubusercontent.com/u/1088089?v=4" width="100px;"/><br /><sub><b>Daniel Mahon</b></sub>](https://www.mahonstudios.com)<br />[💻](https://github.com/netlify/netlify-cms/commits?author=danielmahon "Code") |
+| [<img src="https://avatars3.githubusercontent.com/u/366688?v=4" width="100px;"/><br /><sub><b>Taylor D. Edmiston</b></sub>](http://blog.tedmiston.com/)<br />[📖](https://github.com/netlify/netlify-cms/commits?author=tedmiston "Documentation") | [<img src="https://avatars2.githubusercontent.com/u/1088089?v=4" width="100px;"/><br /><sub><b>Daniel Mahon</b></sub>](https://www.mahonstudios.com)<br />[💻](https://github.com/netlify/netlify-cms/commits?author=danielmahon "Code") | [<img src="https://avatars1.githubusercontent.com/u/16711653?v=4" width="100px;"/><br /><sub><b>Evan Hennessy</b></sub>](https://www.hennessyevan.com)<br />[🔌](#plugin-hennessyevan "Plugin/utility libraries") |
 <!-- ALL-CONTRIBUTORS-LIST:END -->
 
 This project follows the [all-contributors](https://github.com/kentcdodds/all-contributors) specification. Contributions of any kind welcome!