Maas: openstack service checks should support v2 or v3

Created by: stevelle

This affects glance-api checks, cinder-api checks, etc.

Imported comments:

By stevelle on 2015-11-18 00:40:58 UTC

Scope of change shouldn't be that bad thanks to this https://github.com/rcbops/rpc-openstack/commit/9729b8b3727d108806d1a6e6b4eeb0a6d66d5d33

By stevelle on 2015-11-18 23:35:21 UTC

outline of likely solution is going to require specifying an extra arg to each check plugin: --auth-version "v2.0"

This makes a smaller impact on the checks than most alternatives.