Improve the Dashboard layout

- make the category text header taller and centered

See bug #13140648 Settings needs to support the new Quantum Paper theme

Change-Id: I557211db923f106a83d65d090ce610c76fa53d5e

res/layout/dashboard_category.xml

@@ -22,9 +22,10 @@
 
     <TextView android:id="@+id/category_title"
             android:layout_width="match_parent"
-            android:layout_height="wrap_content"
+            android:layout_height="@dimen/dashboard_category_title_height"
             android:singleLine="true"
             android:ellipsize="marquee"
+            android:gravity="center_vertical"
             android:textAppearance="?android:attr/textAppearanceMedium"
             android:textAlignment="viewStart"
             />

res/values/dimens.xml

@@ -88,4 +88,6 @@
     <!-- Dashboard padding between each tiles within the layout -->
     <dimen name="dashboard_cell_gap">4dp</dimen>
 
+    <dimen name="dashboard_category_title_height">48dp</dimen>
+
 </resources>