openstack: rework floating IP handling
openstack: rework floating IP handling

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

Conflicts:
	teuthology/openstack/__init__.py

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