add config setting

in order for the Successes channel to be populated,have to set config.Producer.Return.Successes to true

examples/http_server/http_server.go

@@ -196,6 +196,7 @@ func newDataCollector(brokerList []string) sarama.SyncProducer {
 	config := sarama.NewConfig()
 	config.Producer.RequiredAcks = sarama.WaitForAll // Wait for all in-sync replicas to ack the message
 	config.Producer.Retry.Max = 10                   // Retry up to 10 times to produce the message
+	config.Producer.Return.Successes = true
 	tlsConfig := createTlsConfiguration()
 	if tlsConfig != nil {
 		config.Net.TLS.Config = tlsConfig