Don't use sessions if third party plugin is used
Don't use sessions if third party plugin is used

If an auth_plugin is used do not try to load the session
from the default keystone providers.

Change-Id: If2a87e23cabde006833de70e5c7aa066d95dbf50
Closes-Bug: #1380729

scottdangelo/cinderclient-api-microversions,scottdangelo/cinderclient-api-microversions,eayunstack/python-cinderclient,eayunstack/python-cinderclient