Added data members to COVGame.

Store redundant information (objectId, managerName) in strings in
COVGame so that we can easily access them without lookup in the
gameHistory VC.
Added function to get game state in string form.
Changed game creation

…to store a copy of COVGame’s objectId as a string, This has to happen
after we save/initialize the game because the game’s objectId is null
before saving it.
Added link to the game history VC to home screen.
Implemented game history VCs.