deploy / undeploy / update on the ControlledDynamicWebAppCluster

This works & tested.  However, need to discuss the following

=> resize etc the cluster.  Currently, the war will not propagate to new cluster members.  We should at least store the URL from where it was fetched and auto-push. 
=> are there any subclasses (Cluster of ...) that need these as well?
=> What if the war file at the URL changes? or vanishes?  what is the predictble behavior?
as it stands i'm not sure this is necessary.  if you `deploy` an updated war, i thought appservers were smart about replacing them (and with minimal downtime).

now a rolling update strategy here -- where we do this one-first, then multiple, etc (and removing nodes from nginx in the process!) -- that would be useful!