Make the openstack_citest postgres user superuser.

Make the openstack_citest postgres user (added to Jenkins slaves'
postgres servers a postgres superuser). This will hopefully allow the
nova postgres tests to run.

Also, remove the database_grant that was previously being performed.
This was unnecessary as the postgresql::db['openstack_citest'] define
was taking care of the grant.

Change-Id: Ib43a4acd19f8460de7ddf9f593b0dcd73fb6467c
Reviewed-on: https://review.openstack.org/20947
Reviewed-by: Jeremy Stanley <fungi@yuggoth.org>
Approved: Clark Boylan <clark.boylan@gmail.com>
Reviewed-by: Clark Boylan <clark.boylan@gmail.com>
Tested-by: Jenkins