Follow up patch on missed IdentityV2 methods

This patch addresses other functions of identityv2 client which
are left out in https://review.openstack.org/#/c/216109/

partially implements: blueprint method-return-value-and-move-service-clients-to-lib

Change-Id: I804dce0ec4816ef8230207a1fad031e496fc1bce
3 files changed