Add missing configuration steps for the heat installation

Heat requires additional configurations to be able to use more advanced
template features:
- a heat_stack_user role must be defined
- heat_metadata_server_url and heat_waitcondition_server_url must be
  defined

Change-Id: I3dde4c0620ef675c6d80debdbad0170c49a82558
Closes-Bug: #1311998
Merge "Add missing configuration steps for the heat installation"