Make create_server_group 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 create_server_group use **kwargs.

Partially implements blueprint consistent-service-method-names

Change-Id: I543b61fe8e87faa219eb5485cf4fcb0f8e926c14
2 files changed