core: Remove PropertyCompat

PropertyCompat was an empty extension to PropertyInfo, with no
additional logic of it's own, and hence pretty redundant.

This patch removes it, replaces the single place it was used
(TypeCompat) with PropertyInfo and renames the test accordingly.

Change-Id: I21cfe23038e2647ee7ce816b532cb28f067ac826
Signed-off-by: Allon Mureinik <amureini@redhat.com>