Provide defaults for openstack client and novnc revs.
Provide defaults for all nova_common config values.

Also, bump nova rev to stable/havana.
Provide a default value for neutron_rev.

And bump it to stable/havana.
Provide default value for cinder rev of stable/havana.
Provide default value of glance rev of stable/havana.
Add default value for keystone rev of stable/havana.
Restart openstack services when code or config changes.

using new library/restart_if_present.
Rename novnc and neutron common defaults to match convention.
Merge pull request #82 from blueboxgroup/use-defaults

Update to stable/havana