Prune the DVM

[rhc54]

Will fill in later - basic idea is that we are now able to "expand" the DVM (e.g., with add-host and add-hostfile), but we would also like the ability to "shrink" the DVM by removing select nodes. Two options: remove once all active procs are done on that node, ensuring we don't spawn any new ones there; and flat out just tell the daemon on that node to kill any running procs and die. Need to "heal" the routing tree around the removed daemon.