Make interfaces_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 interfaces_client use **kwargs.

Partially implements blueprint consistent-service-method-names

Change-Id: I18a1b5cd224912f937f1ea39ff0053bf5e6b36ff
3 files changed