add borderless thumbnails, "bubble" refactor

Closes #2430

// FREEBIE

src/org/thoughtcrime/securesms/ConversationAdapter.java

@@ -116,7 +116,6 @@ public class ConversationAdapter extends CursorAdapter implements AbsListView.Re
       default: throw new IllegalArgumentException("unsupported item view type given to ConversationAdapter");
     }
 
-    bindView(view, context, cursor);
     return view;
   }