Changes

Bug 535647 - Deleting a reference property allocated to a resource,
wrongly deletes the property itself
Added special logic so that a reference property is deleted in the same 
way as a literal property. namely, by deleting the allocation, and not 
the property itself. Default behaviour in Sirius is to delete the
property element, which is not the desired effect here.
Change-Id: I71c81baee9f13d51f1b9dd5157707781820396e7 Signed-off-by: Jad
El-khoury <jad@kth.se>