Implement redesign, refactor everything

- Write CSS for everything, update templates.
- Refactor discussion view. Stream is split into two components
(content and scrubber) which have their own responsibilities.
- Extract pane functionality into a mixin.
- Implement global “back button” system. You give a “paneable” target
to the application controller, the back button will modulate its
pane-related properties as necessary, and call an action when the
button is clicked.
- Extract welcome-hero into its own component.
- Lots of other general improvements/refactoring. The code is quite
well-commented so take a look!

ember/app/components/discussions/post-wrapper.js

@@ -0,0 +1,62 @@
+import Ember from 'ember';
+
+import TaggedArray from '../../utils/tagged-array';
+import ActionButton from '../ui/controls/action-button';
+
+export default Ember.Component.extend({
+	tagName: 'article',
+	layoutName: 'components/discussions/post-wrapper',
+
+	// controls: null,
+
+	post: Ember.computed.alias('content'),
+
+	contentComponent: function() {
+		return 'discussions/post-content-'+this.get('post.type');
+	}.property('post.type'),
+
+	classNames: ['post'],
+	classNameBindings: ['post.deleted', 'post.edited'],
+
+	// construct: function() {
+	// 	// this.set('controls', Menu.create());
+
+	// 	// var post = this.get('post');
+
+	// 	// if (post.get('deleted')) {
+	// 	// 	this.addControl('restore', 'Restore', 'reply', 'canEdit');
+	// 	// 	this.addControl('delete', 'Delete', 'times', 'canDelete');
+	// 	// } else {
+	// 	// 	if (post.get('type') == 'comment') {
+	// 	// 		this.addControl('edit', 'Edit', 'pencil', 'canEdit');
+	// 	// 		this.addControl('hide', 'Delete', 'times', 'canEdit');
+	// 	// 	} else {
+	// 	// 		this.addControl('delete', 'Delete', 'times', 'canDelete');
+	// 	// 	}
+	// 	// }
+	// }.on('init'),
+
+	didInsertElement: function() {
+		var $this = this.$();
+		$this.css({opacity: 0});
+
+		setTimeout(function() {
+			$this.animate({opacity: 1}, 'fast');
+		}, 100);
+	},
+
+	addControl: function(tag, title, icon, permissionAttribute) {
+		if (permissionAttribute && ! this.get('post').get(permissionAttribute)) {
+			return;
+		}
+
+		var self = this;
+		var action = function(post) {
+			self.get('controller').send(actionName, post);
+		};
+
+		var item = MenuItem.extend({title: title, icon: icon, action: action});
+		this.get('controls').addItem(tag, item);
+	}
+
+});