Fixed board being flipped when restarting game

How to reproduce:
-Start a multiplayer game as a client
-Quit the game
-Start a single player game

The board will be flipped, because the IsServer bool in BoardLoader was
set to false, meaning the board will be flipped.

Fixed by adding a check to IstTwoPlayer. If is not two player -> set
IsServer in BoardLoader to true.
Fixed bug with remote player lives not being updated

How to reproduce :
-Start a multiplayer game
-Let a player loose a life

The life count for that player on the other client will not be reduces.

Fixed by adding a call to ReducePlayerLives in RemoveBall()