Merge branch '576-empty-state-messages-are-briefly-shown-when-they-shouldn-t' into 'master'

Prevent empty state messages from showing briefly

When we clear a list in `onPause()`, the proper behavior is that the empty state
message is shown, because the list is indeed empty.

However, we will reload the list content again in `onResume()`,
so the fix chosen in this MR is to force showing the progress bar
right after clearing the list.

Closes #576

See merge request !267

briar-android/src/org/briarproject/android/forum/ForumListFragment.java

@@ -119,6 +119,7 @@ public class ForumListFragment extends BaseEventFragment implements
 		super.onPause();
 
 		adapter.clear();
+		list.showProgressBar();
 		list.stopPeriodicUpdate();
 	}