second attempt to fix hostgroup ordering for orchestration

Rather than messing with custom sql, this PR just removes the
attempt at ordering child_hostgroups in the association.
Instead, we call .reorder() explicitly in deploy.rb where
we attempt to deploy the hosts.
Merge pull request #35 from jtomasek/models2

Wire models with wizard steps 2 and 3
Merge pull request #41 from sseago/deploy_order_fix2

second attempt to fix hostgroup ordering for orchestration
Use host stats to check host ready