log response time

lib/response.js

@@ -29,7 +29,7 @@ module.exports = function(request, response, result) {
   });
 
   response.on("finish", function() {
-    logging.log(request.id, response.statusCode, "(" + (human_status[result.status] || "-") + ")");
+    logging.log(request.id, response.statusCode, headers["Response-Time"] + "ms", "(" + (human_status[result.status] || "-") + ")");
   });
 
   response.on("error", function(err) {