Merge branch '03-PlayerPrefab' of https://github.com/GeekyMonkey/ScratchyUnitySpaceInvaders into 03-PlayerPrefab
Add space invaders aliens 1 + 2
3 SI + 10 Galaga alien prefabs
Alien animation script
Merge branch '05-AlienAnimation' of https://github.com/GeekyMonkey/ScratchyUnitySpaceInvaders into 05-AlienAnimation