openstack: enforce hints as an array
openstack: enforce hints as an array

All OpenStack hints have been converted to arrays (hammer, infernalis,
master), raise an error if a hint is added old style to avoid mixing
style.

http://tracker.ceph.com/issues/13581 Fixes: #13581

Signed-off-by: Loic Dachary <b6eae37fc74638590e3f9030895d42446505d41b@dachary.org>

SUSE/teuthology,ceph/teuthology,ceph/teuthology,dmick/teuthology,ktdreyer/teuthology,ktdreyer/teuthology,SUSE/teuthology,dmick/teuthology,dmick/teuthology,SUSE/teuthology