fix LoaderManager inefficiencies

Redundant calls in ConversationActivity and ConversationListActivity
was causing unnecessary view invalidations.

Closes #2592

src/org/thoughtcrime/securesms/ConversationListFragment.java

@@ -96,8 +96,6 @@ public class ConversationListFragment extends ListFragment
     });
     initializeListAdapter();
     initializeBatchListener();
-
-    getLoaderManager().initLoader(0, null, this);
   }
 
   @Override