Ensure Nova Network-compatible demo provisioning

Due to a limitation in the implementation of openstack::provision,
demo provisioning was previously limited to deployments with
Neutron.  This change adds support for provisioning users and
images and configuring tempest for deployments using Nova Network.

Closes-Bug: #1242668

Change-Id: Ic5d35e1f0f4f1fb8815193a7573955952dd698e4