added ability to remove player from group by id
added ability to remove player from group by id

ARISGames/server,tl-its-umich-edu/ARISGames-server,ARISGames/server,tl-its-umich-edu/ARISGames-server,ARISGames/server,tl-its-umich-edu/ARISGames-server,tl-its-umich-edu/ARISGames-server,ARISGames/server