As Player, I want to be notify when someone won the game

[KunL21]

acceptance test:

1. start the game and click play
2. Wait for the timer to count down to zero on the top to enter a battle
3. The hp will be deducted each battle
4. wait for your own hp or your opponent's hp went down to zero after each battle
5. a message will display whether the player won or lose the game