Make keypairs_client 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 keypairs_client use **kwargs.

Partially implements blueprint consistent-service-method-names

Change-Id: I4d2b0a9a933884333159b00a7a8b5e8ceddfe325
9 files changed