(TK-92) Add graceful-shutdown support

Add graceful-shutdown support to the Jetty9 Webservice. Now,
when the webserver is shutdown, the server will give open
requests a chance to resolve themselves. Allow user to
configure the graceful shutdown stop timeout.
So, I was thinking that if someone set it to zero then that would mean that we didn't do the graceful shutdown behavior at all (e.g., maybe not even add the handler?)  @camlow325 we talked about this before, do you have an opinion?