Introduce OpenStack Heat as additional provisioner

ONAP will mainly be installed on a Kubernetes cluster installed
on Openstack. The creation of the resources (instances, networks, etc.)
are done using Heat so this change prepares the engine for Heat
introduction by adding 2 new parameters:
- provisioner: it can be set by using -r
- uri to heat template: it can be set by using -t

Change-Id: Iedf7848519487a35a2cf5c823e23d6ba72bdb006
29 files changed