Set 0 nodes for devstack-f20-virt-preview

I created this node type and associated job.  It's not working and
I've switched gears toward working toward a CentOS based solution.
Start by setting this node type to 0 ready so nodepool will clean up
anything running.

Change-Id: If2cfa2c048d2ab9197378e30926a81b80b31e069
Merge "Set 0 nodes for devstack-f20-virt-preview"