Update WebSocketsClient.cpp

fix #140 Socket.io client doesn't reconnect to server

src/WebSocketsClient.cpp

@@ -331,6 +331,7 @@ void WebSocketsClient::clientDisconnect(WSclient_t * client) {
     client->cVersion = 0;
     client->cIsUpgrade = false;
     client->cIsWebsocket = false;
+    client->SessionId = "";
 
     client->status = WSC_NOT_CONNECTED;