Make identity v3 users_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 users_client use **kwargs.

Partially implements blueprint consistent-service-method-names

Change-Id: I8b4e2059a9a8d4be1df5aab1de8a4339e97679d2
14 files changed