Updated trove client to support Keystone V3 API. The
Keystoneclient session object is used for authentication, retrieving
the service catalog and HTTP connection/session management.
Added additional CLI parameters for Keystone V3.
Added tests using requests_mock instead of mocking completely the
session object like the previous failed patch:
https://review.openstack.org/#/c/102315
Change-Id: Ib804c0a45b3b4d3f8670ec642b2c2fd1be6cd656