Updated openstack/openstack
Project: openstack-dev/devstack  bfa5817c5085d84b2d6b821f000c8f028c61f565

Add rhel7 as supported distro

rhel7 testing has been fairly stable with redhatci bot testing beta
and RC builds for some time.  Centos7 testing is now coming online
with the nightly builds.  Thus no need to require the unsupported flag
any more.

Change-Id: Iceab5c1d8b713f1f96b5751cf988fe060cfeff58