Introduce flight for stable branches of OpenStack

Introduce flight for stable branches of OpenStack

OpenStack have many different repo which should be in sync, so this
patch should grab the revisions of the stable branch of every OpenStack
tree. Tempest does not have stable branch and should be able to test any
OpenStack version.

This patch also create flight for the latest release of OpenStack named
Ocata instead of testing branch master, as the scripts are not yet ready
to test it.

Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>