improve notification broadcast

lib/wsapp.js

@@ -29,7 +29,10 @@ WsApp.start = function(server) {
   var io = require('socket.io')(server);
 
   WalletService.onNotification(function(serviceInstance, args) {
-    io.to(serviceInstance.walletId).emit('notification', args);
+    var room = serviceInstance.walletId || args.walletId;
+    if (room) {
+      io.to(room).emit('notification', args);
+    }
   });
 
   io.on('connection', function(socket) {