Adds support for passing extra tenant attributes to keystoneclient

    Patch adds simple kwargs passthrough to tenant update and create
    methods allowing users to exercise the extras functionality
    of keystone.

    As-per keystone data model docs:
    http://docs.openstack.org/developer/keystone/architecture.html#data-model

    Fixes: bug #1220790

Change-Id: Ie02c9b5ae5fc4ec394e98d284c5c8516c73e04c3
Merge "    Adds support for passing extra tenant attributes to keystoneclient"