Make update_server 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_server use **kwargs.

Partially implements blueprint consistent-service-method-names

Change-Id: Iac517acbd80d8140461b3e8853573add1ab4a9eb
1 file changed