Add some system packages to package list adapter.

As we're using the adapter for notification control stuff, we need to
include those packages, too, as they're throwing notifications as well.

Also optimize code a little.

Change-Id: I8829041a535923e3d93d9566e27eb99c48f25abd

Conflicts:
	src/com/android/settings/cyanogenmod/PackageListAdapter.java