client/general: refactor all the things

- Move controls to the "controls/" directory
- Make controls interface look similar to each other
- Prefix "private" methods and attributes with underscore

client/js/controllers/comments_controller.js

@@ -5,10 +5,10 @@ const topNavController = require('../controllers/top_nav_controller.js');
 
 class CommentsController {
     registerRoutes() {
-        page('/comments', (ctx, next) => { this.listCommentsRoute(); });
+        page('/comments', (ctx, next) => { this._listCommentsRoute(); });
     }
 
-    listCommentsRoute() {
+    _listCommentsRoute() {
         topNavController.activate('comments');
     }
 }