Update ssh tunneling tool / Setup API for cross project queries 


The tunneling script is useful for setting up a set of SSH tunnel connections on different local ports.  Each port on your local instance corresponds to a different database host accessible from a remote box to which you have SSH access.  In the case of the user metrics API this is helpful for connecting to different hosts where project slaves reside.

This pull request also contains code that allows the backend to properly utilize different db hosts to be accessed.