Add keystone heat support

Heat provides heat::keystone::auth (heat-engine) and
heat::keystone::auth_cfn (cloudformation api) after [1].  This adds
support here

[1] https://review.openstack.org/#/c/45380/

Change-Id: Ib60620b2fcf2305283bd2a3475d78758fd664e22
Merge "Add keystone heat support"