Updates client to work with keystone essex roles API routes.
Updates client to work with keystone essex roles API routes.

Also adds pep8 to requirements since it was missing, and adds the
automatically-created venv to the gitignore list.

Change-Id: Iafa05c1889d7706b79d0f9392a9ac24f2f5a1719

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