Merge "Refactoring the User Switcher layout files to use dimensions in...

Merge "Refactoring the User Switcher layout files to use dimensions in dimens_car.xml and colors_car.xml so that overlays will be easier. Also, added a dialog when adding a user.  Fixed the issue where coming back to the user picker makes the buttons unresponsive" into pi-dev
am: e71fb69e

Change-Id: I42c08bbbfe1a85aa0feca3ea9a00e4891b480dd9