Enable heat-ui plugin for horizon by default
Enable heat-ui plugin for horizon by default

Since the orchestration tab was moved in Horizon into a plugin,
we have a regression if we don't enable that plugin by default.

Change-Id: Ia99b23f3ece61830954f73704e85a6efaa5f7428

dprince/tripleo-heat-templates,openstack/tripleo-heat-templates,openstack/tripleo-heat-templates,dprince/tripleo-heat-templates