Merge pull request #7 from Luit/patch-1

fix RegisterPeerPicker panic string

(Luit has signed the CLA.)
diff --git a/peers.go b/peers.go
index bfa0ab4..a74a79b 100644
--- a/peers.go
+++ b/peers.go
@@ -54,7 +54,7 @@
 // It is called once, when the first group is created.
 func RegisterPeerPicker(fn func() PeerPicker) {
 	if portPicker != nil {
-		panic("RegisterInitPeers called more than once")
+		panic("RegisterPeerPicker called more than once")
 	}
 	portPicker = fn
 }