Add support for response_dict parameter to some swiftclient.client.Connection calls.

swiftclient was [changed in 1.5.0](https://github.com/openstack/python-swiftclient/commit/3f66a8ae6b8d9741809773a9665d4768d2f161a6) to add an optional ``response_dict`` parameter to several ``swiftclient.client.Connection`` methods, which allows for status, reason, and header information to be given back to callers. The ``pyrax.cf_wrapper.client.CFClient`` methods which call into those swiftclient methods were given an optional ``swiftclient_response`` parameter which is passed on.

This fixes #126.