Added new main menu and fail screen.
Merge branch 'master' of https://github.com/luckyb/ZombieFoodTruck

Conflicts:
	Unity/Assets/Art/Zombie/zombie_death_1.png.meta
	Unity/Assets/Art/Zombie/zombie_death_2.png.meta
	Unity/Assets/Sounds/fail.wav.meta
	Unity/Assets/Sounds/success.wav.meta