Add navbar background preview to ThemesContract

Change-Id: Id3ed43c86649b1757fec7f3fc7dee2d2730258e2
Add column for tracking when a theme was installed

Change-Id: Ie8d13aaaf968c21d765062ae598fdac62caa7b2d
Merge changes Ie8d13aaa,Id3ed43c8 into kitkat

* changes:
  Add column for tracking when a theme was installed
  Add navbar background preview to ThemesContract