Upgrade to Ember 1.11-beta.1

HTMLBars goodness! Since there was some breakage and a lot of fiddling
around to get some things working, I took this opportunity to do a big
cleanup of the whole Ember app. I accidentally worked on some new
features too :3

Note that the app is still broken right now, pending on
https://github.com/emberjs/ember.js/issues/10401

Cleanup:
- Restructuring of components
- Consolidation of some stuff into mixins, cleanup of some APIs that
will be public
- Change all instances of .property() / .observes() / .on() to
Ember.computed() / Ember.observer() / Ember.on() respectively (I think
it is more readable)
- More comments
- Start conforming to a code style (2 spaces for indentation)

New features:
- Post hiding/restoring
- Mark individual discussions as read by clicking
- Clicking on a read discussion jumps to the end
- Mark all discussions as read
- Progressively mark the discussion as read as the page is scrolled
- Unordered list post formatting
- Post permalink popup

Demo once that Ember regression is fixed!

ember/app/helpers/user-avatar.js

@@ -30,12 +30,12 @@ export default Ember.Handlebars.makeBoundHelper(function(user, options) {
         return;
     }
 
-    var number;
-    if (number = user.get('avatarNumber')) {
-        number = number + '';
-        var filename = number.length >= 3 ? number : new Array(3 - number.length + 1).join('0') + number;
-        return new Ember.Handlebars.SafeString('<img src="/packages/flarum/core/avatars/'+filename+'.jpg" class="avatar '+options.hash.class+'">');
-    }
+    // var number;
+    // if (number = user.get('avatarNumber')) {
+    //     number = number + '';
+    //     var filename = number.length >= 3 ? number : new Array(3 - number.length + 1).join('0') + number;
+    //     return new Ember.Handlebars.SafeString('<img src="/packages/flarum/core/avatars/'+filename+'.jpg" class="avatar '+options.hash.class+'">');
+    // }
 
 	var username = user.get('username');
     if (!username) {