Make 2 functions in network_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 add_router_interface,remove_router_interface of network_client use **kwargs.

Partially implements blueprint consistent-service-method-names

Change-Id: Ib6e222431c9681d01890bc980547cc2e90923526
14 files changed