mDNS discovery starts announcing right away: does not wait for first interval to elapse.

Closes #256

p2p/discovery/mdns.go

@@ -118,8 +118,7 @@ func (m *mdnsService) pollForEntries(ctx context.Context) {
 
 	ticker := time.NewTicker(m.interval)
 	for {
-		select {
-		case <-ticker.C:
+		//execute mdns query right away at method call and then with every tick
 		entriesCh := make(chan *mdns.ServiceEntry, 16)
 		go func() {
 			for entry := range entriesCh {
@@ -141,6 +140,10 @@ func (m *mdnsService) pollForEntries(ctx context.Context) {
 		}
 		close(entriesCh)
 		log.Debug("mdns query complete")
+
+		select {
+		case <-ticker.C:
+			continue
 		case <-ctx.Done():
 			log.Debug("mdns service halting")
 			return