Merge pull request #11 from changbl/working

Several improvements
Merge pull request #12 from changbl/working

atomic, userdata and checkin_chefserver
Use IP address instead of hostname for chef server url

In multihost nova-network deployment, hostname doesn't always
work. Use IP instead.
Merge pull request #13 from maoy/ip

Use IP address instead of hostname for chef server url
Public IP for gateway, checkin chefserver (all VMs), and periodic poll

* chefserver can checkin (knife bootstrap) itself

* add floating ip to gateway

* periodic poll to check whether all servers are up