This fixes #4

bugfix: missing bullet prefabs on player. also set heal powerup prefab to trigger and changed bullet speed.

Conflicts:
	Assets/Resources/Levels.xml

--> ground prefab needs to be fixed!
Scale: 22, 0.2, 1
sprite: square_anchorLowerLeft.png
BoxCollider: Offset 0.5 0.5,     Size: 1 1

TODO for Tim: Add Bullet prefabs to Player, Add Tag "Trap" to Trap prefab.

For each prefab, each child has to have its unique name.

healthbars are disabled when a player dies.