Make create_flavor 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_flavor use **kwargs.

Partially implements blueprint consistent-service-method-names

Change-Id: Id8ece6064bf98f05b785d89a7018dd00508d0a4c
8 files changed