Include openstack_project for Jenkins' SSH key.

The openstack_project class needs to be included to make the
jenkins_ssh_key variable available to nodes.

Change-Id: I57fb6f24755bf123cf9f6f9b724035d0ababf8f3
Reviewed-on: https://review.openstack.org/31581
Reviewed-by: James E. Blair <corvus@inaugust.com>
Approved: Clark Boylan <clark.boylan@gmail.com>
Reviewed-by: Clark Boylan <clark.boylan@gmail.com>
Reviewed-by: Jeremy Stanley <fungi@yuggoth.org>
Tested-by: Jenkins