Support pluggable boards, display battleships games on the UI

[reddyalready]

Will use this space to agree steps and a specification.

Steps

• Add a Board.ts, and a board instance member to Game.ts here.
• Send board from game server whenever game stats are sent.
• Receive/Persist (to disk?) board in the tournament server.
• Send a subset of boards to the UI during tournaments (as not all need to be send/displayed)
• Make available all boards at the end of a match/tournament (e.g. for players, by click of a UI button, retrieve from server).

Spec

Board.ts

Suggest we have a generic type of board and then allow game implementation to supply a more detailed board, that can be used by a UI renderer (if one exists) to render the more detailed board.

Generic variant: TBD

Detailed examples:

Battleships: TBD

Ultimate TTT: TBD