Stop sending endpoints to the Super Peer

Currently, the super peer knows the endpoints of all its clients. This makes it easy to query the endpoints when establishing a P2P connection. However, from the point of view of privacy it is unpleasant. It would be better if the requesting node would query the end points via the super-peer itself at the other node. This would make central storage overdue. In addition, the node could decide to whom it communicates the endpoints and to whom it does not.