[V3] Make policy_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 policy_client use **kwargs.

Partially implements blueprint consistent-service-method-names

Change-Id: Ic78a5e0b8fb78d88a8f7f974731be5368645af8b
2 files changed