Add which node has been registered with the same name (#1992)

* Add which node has been registered with the same name

Was looking through logs of several nodes that had been launched at the same time and it was getting hard to tell which node was being duplicated. This would allow you do to see the name of the node that caused the issue

* switch to shutdown_node_task

tools/rosmaster/src/rosmaster/registrations.py

@@ -125,7 +125,7 @@ def shutdown_node_task(api, caller_id, reason):
     @type  reason: str
     """
     try:
-        xmlrpcapi(api).shutdown('/master', reason)
+        xmlrpcapi(api).shutdown('/master', "[{}] Reason: {}".format(caller_id, reason))
     except:
         pass #expected in many common cases
     remove_server_proxy(api)