Renamed client side files to match convention.

Gomoku.java is now R2D2ClientGUI.java.
R2D2GameClient.java is now R2D2ClientModel.java.

Also added timestamps to the GUI messages and reversed the order
messages are displayed in so that new messages will bump out old
messages.
Turned on sending game over messages.

Implemented the creation and sending of game over messages from the
GameController.
Minor changes

Deleted App.java as it is unneeded.
Added a simple close method to R2D2Connection to close both streams and
the socket.