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/components/composer/composer-edit.js

@@ -0,0 +1,26 @@
+import Ember from 'ember';
+
+import ComposerBody from 'flarum/components/composer/composer-body';
+
+var precompileTemplate = Ember.Handlebars.compile;
+
+/**
+  The composer body for editing a post. Sets the initial content to the
+  content of the post that is being edited, and adds a title control to
+  indicate which post is being edited.
+ */
+export default ComposerBody.extend({
+  submitLabel: 'Save Changes',
+  content: Ember.computed.oneWay('post.content'),
+  originalContent: Ember.computed.oneWay('post.content'),
+
+  populateControls: function(controls) {
+    var title = Ember.Component.create({
+      tagName: 'h3',
+      layout: precompileTemplate('Editing Post #{{component.post.number}} in <em>{{discussion.title}}</em>'),
+      discussion: this.get('post.discussion'),
+      component: this
+    });
+    controls.pushObjectWithTag(title, 'title');
+  }
+});