adding first iteration of configurable timeout to server port binding
can now get all registered servers from an IOSystem.  This is used in ColossusSpec.withIOSystem to ensure all servers have been shutdown properly.  Removed some redundant "end" calls, since withIOSystem takes care of all the shutting down
tweaked behavior of unbindable behavior:  Server actor now shuts down.  Had to tweak a bit of behavior to allow for Server shutdown, mainly making WorkerManager the sole watcher of a Server, and notifying workers of the termination.
added comment for next bout of work along the "end" function in ColossusSpec
merging master
fixed merge conflicts in ServerSpec.scala and Util.scala
Merge pull request #22 from tumblr/server_registration_config

Server registration config