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-body.js

@@ -0,0 +1,40 @@
+import Ember from 'ember';
+
+import HasItemLists from 'flarum/mixins/has-item-lists';
+
+/**
+  This component is a base class for a composer body. It provides a template
+  with a list of controls, a text editor, and some default behaviour.
+ */
+export default Ember.Component.extend(HasItemLists, {
+  layoutName: 'components/composer/composer-body',
+
+  itemLists: ['controls'],
+
+  submitLabel: '',
+  placeholder: '',
+  content: '',
+  originalContent: '',
+  user: null,
+  submit: null,
+  loading: false,
+  confirmExit: '',
+
+  disabled: Ember.computed.alias('composer.minimized'),
+
+  actions: {
+    submit: function(content) {
+      this.get('submit')({
+        content: content
+      });
+    },
+
+    willExit: function(abort) {
+      // If the user has typed something, prompt them before exiting
+      // this composer state.
+      if (this.get('content') !== this.get('originalContent') && !confirm(this.get('confirmExit'))) {
+        abort();
+      }
+    }
+  }
+});