Themes: Update ThemesContract with install state [1/3]

The ThemesProvider will now be tracking the state of themes as
they are installed, updated, and removed.  Apps that only care
about these three states, when it comes to themes, can simply
register a broadcast receiver to handle these new actions.

Change-Id: I3256f88f5cd6187ebbe9636c8d87b4509aceed61