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/mixins/fade-in.js

@@ -0,0 +1,14 @@
+import Ember from 'ember';
+
+export default Ember.Mixin.create({
+  fadeIn: Ember.on('didInsertElement', function() {
+    var $this = this.$();
+    var targetOpacity = $this.css('opacity');
+    $this.css('opacity', 0);
+    setTimeout(function() {
+      $this.animate({opacity: targetOpacity}, 'fast', function() {
+        $this.css('opacity', '');
+      });
+    }, 100);
+  })
+});