Make identity v3 domains_client use **kwargs

As we discussed on
http://lists.openstack.org/pipermail/openstack-dev/2015-July/068864.html
All http POST/PUT methods need to contain **kwargs as their arguments.

This patch makes identity v3 domains_client use **kwargs.

Also add and correct doc string link.

Partially implements blueprint consistent-service-method-names

Change-Id: Ibe27a399e5b2774aae2c3585e2299616583c25f9
7 files changed