In previous implementation IR handler of `AddPeer` notification didn't send
registration to contract if existing peer changed has changed its
information. as a consequence, the network map members could not update the
information without going into offline.
Change `processAddPeer` handler to check if
* candidate in the network map is a brand new
* or information about the network map member was changed
and call `AddPeer` method if so.
Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>