Started adding sounds.
Merge branch 'master' of https://github.com/luckyb/ZombieFoodTruck
Set up background layers.
Merge branch 'master' of https://github.com/luckyb/ZombieFoodTruck

Conflicts:
	Unity/Assets/Art/Backgrounds/food_truck.png.meta
	Unity/Assets/Art/Backgrounds/food_truck_toplid.png.meta