Corrects error message for ping errors from server behavior

* Modified ServerUnreachable message to return whatever message
  is passed to it
* Modified Windows and Linux clients to pass a full failure message
  rather than just an IP address.

Change-Id: Ifc64b28063b1a3584568711f9ff8e4b77b5be399
Merge "Corrects error message for ping errors from server behavior"