update UDF server to allow defer s.Stop() behavior
update UDF server to allow defer s.Stop() behavior

sputnik13/kapacitor,influxdb/kapacitor,sputnik13/kapacitor,adityacs/kapacitor,influxdb/kapacitor,sputnik13/kapacitor,adityacs/kapacitor,influxdb/kapacitor,adityacs/kapacitor