Fixes #663 Conversation list loads in reverse order

The onChangeActiveAt listener promotes newly activated conversations to
the top of the inbox. By firing on an 'add' event, if the conversation
list happened to load after the inbox frontend was initialized, each new
entry would be incorrectly moved to the top, effectively reversing the
list.

// FREEBIE

js/views/inbox_view.js

@@ -74,7 +74,7 @@
             }).render();
 
             this.inboxListView.listenTo(inboxCollection,
-                    'add change:active_at',
+                    'change:active_at',
                     this.inboxListView.onChangeActiveAt);
 
             this.searchView = new Whisper.ConversationSearchView({