Add postgres server to Jenkins slaves.

Add postgres servers to each non bare Jenkins slave so that tests can be
performed against postgres.

Change-Id: I374afdf2443086e2c5ad42d2e163adbf2d3df74b
Reviewed-on: https://review.openstack.org/20041
Reviewed-by: Jeremy Stanley <fungi@yuggoth.org>
Reviewed-by: Kurt Taylor <krtaylor@us.ibm.com>
Reviewed-by: Sean Dague <sdague@linux.vnet.ibm.com>
Approved: Clark Boylan <clark.boylan@gmail.com>
Reviewed-by: Clark Boylan <clark.boylan@gmail.com>
Tested-by: Jenkins