Add bare-f20 nodes

We have some testing it makes sense to bring up on f20 nodes, as the
package support is better at this point [1].  Also, building nodes
stops bit-rot in the setup scripts.

I have tested this by hand on a rax f20 node.  This requies the 4.0.0
release of puppet-postgresql [3]

[1] https://review.openstack.org/#/c/115752/
[2] https://github.com/puppetlabs/puppetlabs-postgresql/releases/tag/4.0.0
[3] https://review.openstack.org/#/c/117396/

Change-Id: Ia1cfffbffd61d35c8db69f592c99dc2cc865d2c3
Merge "Add bare-f20 nodes"