Render group updates

Not pretty, but it works. Also allows for later localization.
Copy/behavior is borrowed from the Android client.

Closes #104
Fixes #65

js/views/group_update_view.js

@@ -0,0 +1,40 @@
+/* vim: ts=4:sw=4:expandtab
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+(function () {
+    'use strict';
+
+    window.Whisper = window.Whisper || {};
+
+    Whisper.GroupUpdateView = Backbone.View.extend({
+        tagName:   "div",
+        className: "group-update",
+        render: function() {
+            //TODO l10n
+            var messages = ['Updated the group.'];
+            if (this.model.name) {
+                messages.push("Title is now '" + this.model.name + "'.");
+            }
+            if (this.model.joined) {
+                messages.push(this.model.joined + ' joined the group');
+            }
+
+            this.$el.text(messages.join(' '));
+
+            return this;
+        }
+    });
+
+})();