Set openstack_citest owner to openstack_citest.

Set the owner on the postgres openstack_citest DB to the
openstack_citest user. Also, remove openstack_citest's superuser privs.

Change-Id: I98e448ef59b6a27cad0d9732a87ee87f5c4abd5f
Reviewed-on: https://review.openstack.org/21016
Approved: Jeremy Stanley <fungi@yuggoth.org>
Reviewed-by: Jeremy Stanley <fungi@yuggoth.org>
Tested-by: Jenkins