remove useless time.Now call

node/bwmonitor/bwmonitor.go

@@ -68,9 +68,8 @@ func (bw *BandwidthMonitor) Run(stop chan bool) {
 	t := time.NewTicker(bw.period)
 	for {
 		select {
-		case <-t.C:
+		case now := <-t.C:
 			if c, err := getBytesSentForDevice(bw.device); err == nil {
-				now := time.Now()
 				bw.lock.Lock()
 				bw.rate = float64(c-bw.counter) / now.Sub(bw.stamp).Seconds()
 				bw.counter = c