Bugfix: bx in etcd.go didn't get Key

Thus record only diffing in the Key were seen as identical and not
included in the end results. Of course this being a map when and if
this would happen was rather random.

Fixed by including Key. Further small tweaks and code refactors.

middleware/etcd/etcd.go

@@ -103,7 +103,7 @@ Nodes:
 		if err := json.Unmarshal([]byte(n.Value), serv); err != nil {
 			return nil, err
 		}
-		b := msg.Service{Host: serv.Host, Port: serv.Port, Priority: serv.Priority, Weight: serv.Weight, Text: serv.Text}
+		b := msg.Service{Host: serv.Host, Port: serv.Port, Priority: serv.Priority, Weight: serv.Weight, Text: serv.Text, Key: n.Key}
 		if _, ok := bx[b]; ok {
 			continue
 		}