Create PeerInterface.class

Move all the peer communication into a new class, PeerInterface
Todo for this class
-make a method recieveUnknownMessage that identifies a message and runs the relevant function (ie recieveHandshake, recievePiece)
-make method recieveHandshake() to recieve handshakes from a potential peer
-make a method that runs a different message method based on input
-make methods for recieving and sending bittorrent protocol messages that haven't been coded yet
-create a test client to check compatibility with this class