Moved CompareByteArray from Handshake to PeerMessage.
Added an empty constructor to HandshakeMessage.
Implemented ChokeMessage.
Implemented UnchokeMessage.
Implemented InterestedMessage.
Implemented NotInterestedMessage.
Implemented HaveMessage.
Implemented BitfieldMessage.
Implemented Request and Piece messages.
Implemented CancelMessage.
Implemented PortMessage.