Add support for rematches

[averycrespi]

Playing again
POST /games/{name}/{id}/playAgain

{name} (required): the name of the game being played again.

{id} (required): the ID of the previous finished room.

Given a previous room, generates a room ID where users should go if they want to play again. Creates this new room if it didn’t exist before.

Accepts these parameters:

playerID (required): the player ID of the player on the previous game.

credentials (required): player’s credentials.

numPlayers (optional): the number of players. Defaults to the numPlayers value of the previous room.

setupData (optional): custom object that was passed to the game setup function. Defaults to the setupData object of the previous room.

Returns nextRoomID, which is the ID of the newly created room that the user should go to play again.

[averycrespi]

Wait until v0.40 of boardgame.io is released with isGameOver property on getMatch

[averycrespi]

boardgameio/boardgame.io#709