duplicate auth-url option returned by BaseGenericPlugin
duplicate auth-url option returned by BaseGenericPlugin

The free function get_options() should only return the options that
the object itself needs.

Change-Id: Id54f353d8b125807a8fc33b4bca8854605e3febb
Closes-Bug: #1388954

citrix-openstack-build/keystoneauth,jamielennox/keystoneauth,sileht/keystoneauth