Implemented BonusBox message

Improves #20
Improves #8

BonusBoxSpawned messags are now sent each time they a BonusBox is
spawned by either player. The Bonus Box should only need to be sent
once, since its position can't be affected by the player.

TODO:
-The message needs to containt which type of bonus box was spawned.
-A message for when/if the player picks up the BonusBox.
-More bonus types