Adding concept of object ownership change (on peer disconnection and explicitly)

[chrfrantz]

Currently, if a peer leaves the system (or is disconnected), his objects are also removed from the system. Instead of that, an alternative policy (in addition to the existing one for application-dependent choice) should ensure that such objects are not removed but managed by another existing peer (e.g. the longest running peer). If the original peer reconnects, he needs to recognize that he lost ownership of that object.
Ownership should also be explicitly transferrable, i.e. an owner can explicitly choose another peer who should then be responsible for that object.