Themes: Let ThemeService handle all theme processing [1/3]

Only themes that are applied will be processed inside of the
PackageManagerService, all others will be sent off to the
ThemeService.

Signed-off-by: STELIX <ssspinni@gmail.com>

Change-Id: I5f2ec628e1d22a05accc6727efb0c1387455f82f