Use eslint and stylelint, fix all errors (#282)

* Use eslint and stylelint, fix all errors

* Remove jshint, jsbeautify
* Use Object.keys directly since that is available in all major browsers
* Fixes for eslint, stylelint errors
* stylelint is not included in grunt test yet because jquery.uls.mobile.css
  has so many !important and need to figure out whether they are really needed

package.json

@@ -25,10 +25,13 @@
     "Siebrand Mazeland"
   ],
   "devDependencies": {
+    "eslint-config-wikimedia": "0.5.0",
     "grunt": "^1.0.1",
-    "grunt-cli": "^1.2.0",
-    "grunt-contrib-jshint": "^1.0.0",
-    "grunt-contrib-qunit": "^1.2.0"
+    "grunt-eslint": "20.0.0",
+    "grunt-stylelint": "0.8.0",
+    "stylelint": "8.2.0",
+    "grunt-contrib-qunit": "^1.2.0",
+    "stylelint-config-wikimedia": "0.4.2"
   },
   "repository": {
     "type": "git",