sending privhost for worker interconnections

This issue came up on julia.mit.edu where the dns  library was not resolving the public hostname properly - ```host julia.mit.edu``` returns "18.4.43.32" while ```telnet julia.mit.edu``` resolves to "18.87.1.8", and connections to the appropriate port on "18.87.1.8" were failing - hence the workers were unable to connect to each other when an addprocs was done from an external julia session with ```julia.mit.edu``` as the ssh hostname.

Since currently the workers are expected to be directly reachable, this fix will ensure that workers are able to connect to each other even when the public hostname does not resolve correctly on the worker nodes.