Switch to 'start' and 'end' instead of 'left' and 'right'.

We can do this now that our minSdk is 19.

res/layout/recipient_preference_contact_widget.xml

@@ -9,7 +9,6 @@
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:src="@drawable/ic_message_white_24dp"
-               android:layout_marginRight="20dp"
                android:layout_marginEnd="20dp"/>
 
     <ImageView android:id="@+id/call"