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
am: 7fd09024

Change-Id: Ib8261c6ec9bf8d8ca5e8781a17e409372053878f