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/ui/alert-message.js

@@ -0,0 +1,53 @@
+import Ember from 'ember';
+
+import HasItemLists from 'flarum/mixins/has-item-lists';
+import ActionButton from 'flarum/components/ui/action-button';
+
+/**
+  An alert message. Has a message, a `controls` item list, and a dismiss
+  button.
+ */
+export default Ember.Component.extend(HasItemLists, {
+  layoutName: 'components/ui/alert-message',
+  classNames: ['alert'],
+  classNameBindings: ['classForType'],
+  itemLists: ['controls'],
+
+  message: '',
+  type: '',
+  dismissable: true,
+  buttons: [],
+
+  classForType: Ember.computed('type', function() {
+    return 'alert-'+this.get('type');
+  }),
+
+  populateControls: function(controls) {
+    var component = this;
+
+    this.get('buttons').forEach(function(button) {
+      controls.pushObject(ActionButton.create({
+        label: button.label,
+        action: function() {
+          component.send('dismiss');
+          button.action();
+        }
+      }));
+    });
+
+    if (this.get('dismissable')) {
+      var dismiss = ActionButton.create({
+        icon: 'times',
+        className: 'btn btn-icon btn-link',
+        action: function() { component.send('dismiss'); }
+      });
+      controls.pushObjectWithTag(dismiss, 'dismiss');
+    }
+  },
+
+  actions: {
+    dismiss: function() {
+      this.sendAction('dismiss', this);
+    }
+  }
+});