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-discussion.js

@@ -0,0 +1,41 @@
+import Ember from 'ember';
+
+import ComposerBody from 'flarum/components/composer/composer-body';
+
+var precompileTemplate = Ember.Handlebars.compile;
+
+/**
+  The composer body for starting a new discussion. Adds a text field as a
+  control so the user can enter the title of their discussion. Also overrides
+  the `submit` and `willExit` actions to account for the title.
+ */
+export default ComposerBody.extend({
+  submitLabel: 'Post Discussion',
+  confirmExit: 'You have not posted your discussion. Do you wish to discard it?',
+  titlePlaceholder: 'Discussion Title',
+  title: '',
+
+  populateControls: function(items) {
+    var title = Ember.Component.create({
+      tagName: 'h3',
+      layout: precompileTemplate('{{ui/text-input value=component.title class="form-control" placeholder=component.titlePlaceholder disabled=component.disabled autoGrow=true}}'),
+      component: this
+    });
+    items.pushObjectWithTag(title, 'title');
+  },
+
+  actions: {
+    submit: function(content) {
+      this.get('submit')({
+        title: this.get('title'),
+        content: content
+      });
+    },
+
+    willExit: function(abort) {
+      if ((this.get('title') || this.get('content')) && !confirm(this.get('confirmExit'))) {
+        abort();
+      }
+    }
+  }
+});