Use endpoint_override with heat client plugin
Use endpoint_override with heat client plugin

We recently changed heatclient to use endpoint_override
to explicitly specify endpoint rather than changing it
in code 'endpoint_override=endpoint'.

Change-Id: I6367550cb32e2dc61b327ca0a8783ffc800851d0
Closes-Bug: #1643332

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