Factor out common code in test_plan
Factor out common code in test_plan

Change-Id: I26bca9eabc62785cdb0a1bc306ae7a4e072f2474

ed-/python-solumclient,rackerlabs/arborlabs_client,ed-/python-solumclient,rackerlabs/arborlabs_client,stackforge/python-solumclient,openstack/python-solumclient,stackforge/python-solumclient