Updated openstack/openstack
Project: openstack-dev/devstack  1b899cdfc9b3d35a17880499fed8753101793cec

Always install latest EPEL

Having issues with the centos7 job, that seem to be because they use
an old snapshot that hasn't updated to the latest EPEL.  Thus we
re-install it to ensure we're getting the latest.

Change-Id: I7930f3e05ee953dab80b06142c17d6aa70f2c2d1