create "BattleUmpire" class.

The progress of making game
1) apply singleton pattern to "Player", "CardDeck"
2) add attack, underAttack in "Player"
3) change CardDeck usage.
=> essential function call(loadCardDeck, setPlayerCost)
4) remove "MonsterData" class(don't need)
5) remove "CardDeck" member data in "Player"

TODO
implement battle logic in "BattleUmpire"