Make create_image 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_image **kwargs.

Partially implements blueprint consistent-service-method-names

Change-Id: I788c84aae52b34b165fdb220b0f6de1b555b6f22
7 files changed