Webpack (#1367)

* Replace gulp with webpack and npm scripts for JS compilation
* Set up Travis CI to commit compiled JS
* Restructure `js` directory; only one instance of npm, forum/admin are "submodules"
* Refactor JS initializers into Application subclasses
* Maintain partial compatibility API (importing from absolute paths) for extensions
* Remove minification responsibility from PHP asset compiler
* Restructure `less` directory

js/src/common/models/Group.js

@@ -0,0 +1,16 @@
+import Model from '../Model';
+
+class Group extends Model {}
+
+Object.assign(Group.prototype, {
+  nameSingular: Model.attribute('nameSingular'),
+  namePlural: Model.attribute('namePlural'),
+  color: Model.attribute('color'),
+  icon: Model.attribute('icon')
+});
+
+Group.ADMINISTRATOR_ID = '1';
+Group.GUEST_ID = '2';
+Group.MEMBER_ID = '3';
+
+export default Group;