this change adds cinder to the sessions module and updates the cinder
client usage to use sessions and auth plugins.
* adding cinder options to sessions module
* updating sahara.utils.openstack.cinder to use sessions and auth
* fixing minor mistake in nova session generator
* adding tests for cinder session
* fixing tests for cinder client
Change-Id: I494d9e1ac203609f58587904bbab92d3c8b3f879
Partial-Implements: blueprint keystone-sessions