Insert keychange advisories

On click, these open a verification panel for the relevant contact,
within this conversation.

// FREEBIE

js/views/message_list_view.js

@@ -46,6 +46,8 @@
             var view;
             if (model.isExpirationTimerUpdate()) {
                 view = new Whisper.ExpirationTimerUpdateView({model: model}).render();
+            } else if (model.get('type') === 'keychange') {
+                view = new Whisper.KeyChangeView({model: model}).render();
             } else {
                 view = new this.itemView({model: model}).render();
                 this.listenTo(view, 'beforeChangeHeight', this.measureScrollPosition);