Use both endpoint and endpoint_override
Use both endpoint and endpoint_override

Use both endpoint and endpoint_override to support
python-heatclient<1.6.0.

Change-Id: Ifb13ce90ee3e4063c2e16cf0a3cda1817dc45d29
Related-Bug: #1643507

noironetworks/heat,openstack/heat,noironetworks/heat,openstack/heat