[Provision] Don't provision glance images if Glance wasn't installed

Change-Id: I307a1c273d3a410edd69eade880b93ccddb17ae6
Resolves: rhbz#1175726
(cherry picked from commit 665d11a07736d9f63999bdff0471d5d98a56b6b2)
Merge "[Provision] Don't provision glance images if Glance wasn't installed" into juno