Keystone domain for Heat

This patch adds support for configuring Keystone domain for Heat
via heat-keystone-setup-domain script. It should be reverted
as soon as Keystone v3 is fully functional.

This patch won't be fully functional without either python-keystoneclient
fix [1] or workaround [2].

[1] https://bugs.launchpad.net/python-keystoneclient/+bug/1452298
[2] https://review.openstack.org/180563

Change-Id: Ie9cdd518b299c141f0fdbb3441a7761c27321a88
Co-Authored-By: Jiri Stransky <jistr@redhat.com>
Depends-On: Ic541f11978908f9344e5590f3961f0d31c04bb0c