add media library

* rebase editorial workflow pull requests when behind

* fix async/await transpilation

* add media library pagination

* switch media library to grid layout

* ensure that only cms branches can be force updated

example/config.yml

@@ -1,5 +1,7 @@
 backend:
-  name: test-repo
+  name: github
+  repo: netlify/netlify-cms
+  branch: pr-554-backend
 
 media_folder: "assets/uploads"