CM11 Themes: Add support for composed icons [1/2]

If an icon pack includes background, mask, and/or foreground
images and an icon is not included for a given app, an icon
will be generated using the background, mask and foreground.

Change-Id: I0f5fd7de4f0eae485139cbcd282c1d1e1663952f

Conflicts:
	core/java/android/content/pm/IPackageManager.aidl
	services/java/com/android/server/pm/PackageManagerService.java