Make add_dhcp_agent_to_network  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_dhcp_agent_to_network of network_client.py
use **kwargs.

Partially implements blueprint consistent-service-method-names

Change-Id: I358b96723a97070673a6020994c082fbd6c1cfe7
2 files changed