Add touch feedback and focus on Dashboard tiles

- use a touch-feedback background
- declare DashboardTileView as focusable

Change-Id: I67ae19cd20374e531660232034528c995f595900

src/com/android/settings/dashboard/DashboardTileView.java

@@ -53,6 +53,8 @@ public class DashboardTileView extends FrameLayout implements View.OnClickListen
         mStatusTextView = (TextView) view.findViewById(R.id.status);
 
         setOnClickListener(this);
+        setBackgroundResource(R.drawable.dashboard_tile_background);
+        setFocusable(true);
     }
 
     public TextView getTitleTextView() {