Hide ProgressBar on network error

Based on #5.

app/src/main/java/com/luca0n/joguitos/pluck/activities/TriviaGameActivity.java

@@ -164,6 +164,9 @@ public class TriviaGameActivity extends BaseActivity
         String msg = getResources().getString(R.string.error_network);
         Fragment errorFragment = TriviaGameErrorFragment.newInstance(msg);
 
+        // Hide the progress bar.
+        progressBar.setVisibility(View.GONE);
+
         FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
         ft.replace(R.id.frame_trivia_game, errorFragment);
         ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);