Give openstack_citest createdb perms.

The nove postgres unittests need CREATE DATABASE permissions. Give the
openstack_citest postgres user this ability.

Change-Id: I55f6855dadd0a77f651633c780dd88fcb409a155
Reviewed-on: https://review.openstack.org/21023
Approved: Clark Boylan <clark.boylan@gmail.com>
Reviewed-by: Clark Boylan <clark.boylan@gmail.com>
Reviewed-by: Kurt Taylor <krtaylor@us.ibm.com>
Tested-by: Jenkins