Make update_agent 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 update_agent of network_client use **kwargs.
Also added LP bug detail for add_router_to_l3_agent.

Partially implements blueprint consistent-service-method-names

Change-Id: Id5807a53b839f301517c18af76052a0752e39b9e
2 files changed