Fix OpenStack to properly handle tenants

OpenStack instances show up differently now in CFME
* 5.2 - All instances across all tenants are discovered even if the
  current user doesn't have access.
* 5.3 - Only the instances to which the user has access are discovered,
  this is the _member_ role, not necessarily the admin role, which means
  that though a machine is discovered, it _may_ not be editable.
Merge pull request #1230 from psav/fix_os_instances

Fix os instances