Commit transaction on object delete

The postgres gate jobs currently have an intermittent failure
where a deleted resource shows up in the resource list.

This change does a transaction commit on object delete, which
brings delete behaviour in line with soft_delete behaviour
(soft_delete uses update_and_save, which also commits).

Change-Id: I5e1be4c197863fde3149c964f992ad816db88b7e
Closes-Bug: #1370865
Merge "Commit transaction on object delete"