added constructor to receiver thread, made server thread create and run
a receiver when handling a connection
list of senders in node and related methods, creation of a sender when
handling new connection in server thread
added MessageFactory - can currently create RegisterRequests only
the /actual/ factory (forgot to add it...)
added functionality for starting a server thread to node classes

token message handling in register

added getPort() method to server thread for ease
added Client (the mirror of ServerThread, it handles outgoing connection
requests from a Node)
initial 'down and dirty' message sending for testing - MessagingNode now
sends a register request to Registry upon starting up

debug flag, debugging output in several classes