implementing contact_server

modified:   pong.erl
further implementation

modified:   pong.erl
	implemented: init_server
	implemented: read_config
	implemented: wait_players
	implemented: player_connection
	implemented: game_loop
	new: receive_inputs
	new: update_GameState
	new: flip_GameState
further implementation

modified:   pong.erl
	modified: receive_inputs
	implemented: update_GameState
	implemented: update_player
	implemented: update_ball
	implemented: flip_GameState