Clean up inbox/compose view rendering and swapping

Templatize the inbox view and use the same pattern for in-window view
switching as is now used with the conversation/message detail views.
This means doing more with markup and less jquery manipulation of
individual subelements of the inbox view.

js/index.js

@@ -22,7 +22,7 @@
     if (textsecure.storage.getUnencrypted("number_id") === undefined) {
         window.location = '/options.html';
     } else {
-        new Whisper.InboxView({el: $('body')});
+        new Whisper.InboxView().$el.prependTo($('body'));
         textsecure.storage.putUnencrypted("unreadCount", 0);
         extension.navigator.setBadgeText("");
     }