Add missing tempest inclusion for patch 529515
Add missing tempest inclusion for patch 529515

Patch https://review.openstack.org/529515/ had a problem in the tempest
configuration, it was missing the enabling of the tempest service, thus
causing the tempest builds to fail even more.

Change-Id: If4b5d7e9488e7676c281198107701409a1d457a5
Related-Bug: #1737889

openstack/dragonflow,openstack/dragonflow,openstack/dragonflow