Bug fix: QObject::disconnect called when connection over websocket is closed.
Bug fix: QObject::disconnect called when connection over websocket is closed.

Replaced with QWebSocket::close.

This bug was reported by Seunghyo Lee.

KonstantinRitt/qmqtt,KonstantinRitt/qmqtt,KonstantinRitt/qmqtt,KonstantinRitt/qmqtt