Choose whether to deploy/update using heat.

Let the undercloud script to chose whether to deploy/update the
stack using heat. based on:
I26f91980971fd4598b043bdb764359ac32a3c42a

Change-Id: Iaa6a11c080dd77f45b7a2e85cbb06d2769947be0
Merge "Choose whether to deploy/update using heat."