chore: move local dev env to netlify-cms (#1538)

packages/netlify-cms-core/package.json

@@ -10,7 +10,6 @@
     "dist/"
   ],
   "scripts": {
-    "watch": "webpack-dev-server --hot --open",
     "build": "cross-env NODE_ENV=production webpack"
   },
   "keywords": [
@@ -70,10 +69,8 @@
   "devDependencies": {
     "cross-env": "^5.2.0",
     "css-loader": "^1.0.0",
-    "friendly-errors-webpack-plugin": "^1.7.0",
     "to-string-loader": "^1.1.5",
     "webpack": "^4.16.1",
-    "webpack-cli": "^3.1.0",
-    "webpack-dev-server": "^3.1.5"
+    "webpack-cli": "^3.1.0"
   }
 }