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/admin/index.js

@@ -0,0 +1,28 @@
+import 'expose-loader?$!expose-loader?jQuery!jquery';
+import 'expose-loader?m!mithril';
+import 'expose-loader?moment!moment';
+import 'expose-loader?m.bidi!m.attrs.bidi';
+import 'bootstrap/js/affix';
+import 'bootstrap/js/dropdown';
+import 'bootstrap/js/modal';
+import 'bootstrap/js/tooltip';
+import 'bootstrap/js/transition';
+
+import AdminApplication from './AdminApplication';
+
+const app = new AdminApplication();
+
+// Backwards compatibility
+window.app = app;
+
+export { app };
+
+// Export public API
+
+
+// Export compat API
+import compat from './compat';
+
+compat.app = app;
+
+export { compat };