Added networking to the Layout model

FIXME: not merge-worthy yet, but I wanted to get this
work-in-progress out there before I'm offline for a couple
days.

Refactor Layout to have a unique key of (name, networking)
in order to treat, for example. "HA Nova" and "HA Neutron"
as separate layouts. The UI will still expose this at
deployment time as a choice of a named layout and a
type of networking.
Add additional :through association to get roles from deployments

This isn't ready to merge. It's not tested yet, and it may need
some tweaks for the association itself to work properly.
Added deploy_order to layout role association
add Role/Service/Layout/Parameter data to seeds.rb

This is a work in progress, not yet ready to merge