Call setup once in unit tests

Calling it twice will cause testtools to fail.
This applies to load balancer, vpn, and firewall unit tests.

Change-Id: If9068d706093ff24602dbb1000f599b2479616c8
metaplugin: use correct parameter to call neutron client

Use region_name instead of auth_region.

Change-Id: Ia4640f282de6d781f4f2d5b35da93afa4a88b6bb
Closes-Bug: 1252982
(cherry picked from commit 86617741bcbe040cc95f1fb733525895725279b3)
Merge remote-tracking branch 'upstream/stable/havana' into ovx