Added DEEP_DELETE Action for removing items from the system.
Added a notification of DEEP_DELETE to let the DB know the item really
is deleted
Added delete(Product) method. This is used when undoing the creation of
a product, and could be used when deleting a Product from the root
StorageUnit.
Added call to ProductManager.delete(Product) when undoing the creation
of a Product. ProductManager.unmanage() no longer truly deletes the
Product.
Added functionality for DEEP_DELETE on Product and Item