Add touch feedback and focus on Dashboard tiles

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

Change-Id: I67ae19cd20374e531660232034528c995f595900
diff --git a/res/drawable/dashboard_tile_background.xml b/res/drawable/dashboard_tile_background.xml
new file mode 100644
index 0000000..55cb4c9
--- /dev/null
+++ b/res/drawable/dashboard_tile_background.xml
@@ -0,0 +1,23 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (C) 2014 The Android Open Source Project
+
+     Licensed under the Apache License, Version 2.0 (the "License");
+     you may not use this file except in compliance with the License.
+     You may obtain a copy of the License at
+
+          http://www.apache.org/licenses/LICENSE-2.0
+
+     Unless required by applicable law or agreed to in writing, software
+     distributed under the License is distributed on an "AS IS" BASIS,
+     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+     See the License for the specific language governing permissions and
+     limitations under the License.
+-->
+
+<touch-feedback xmlns:android="http://schemas.android.com/apk/res/android"
+                android:tint="?android:attr/colorButtonPressed">
+    <item>
+        <color android:color="@android:color/white" />
+    </item>
+</touch-feedback>
+