Update for bug #17521147 Settings activity looks terrible on Volantis

Per UX request:

- remove PreferenceHeader list divider
- make list item primary/secondary text using the correct themed list item
text appearance (so that they can be overridden)

Change-Id: Ie0cadf81914cf208434a342829a48b5a1df62141

Author: Fabrice Di Meglio

core/res/res/layout/preference_header_item_material.xml

@@ -45,7 +45,7 @@
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"
             android:singleLine="true"
-            android:textAppearance="?android:attr/textAppearanceMedium"
+            android:textAppearance="?android:attr/textAppearanceListItem"
             android:ellipsize="marquee"
             android:fadingEdge="horizontal" />
 
@@ -54,7 +54,7 @@
             android:layout_height="wrap_content"
             android:layout_below="@android:id/title"
             android:layout_alignStart="@android:id/title"
-            android:textAppearance="?android:attr/textAppearanceSmall"
+            android:textAppearance="?android:attr/textAppearanceListItemSecondary"
             android:ellipsize="end"
             android:maxLines="2" />
 

core/res/res/layout/preference_list_content_material.xml

@@ -48,7 +48,8 @@
                 android:drawSelectorOnTop="false"
                 android:cacheColorHint="@color/transparent"
                 android:listPreferredItemHeight="48dp"
-                android:scrollbarAlwaysDrawVerticalTrack="true" />
+                android:scrollbarAlwaysDrawVerticalTrack="true"
+                android:divider="@null" />
 
             <FrameLayout android:id="@+id/list_footer"
                     android:layout_width="match_parent"