Create animations

[JohnSegerstedt]

• [x] * Zombie move
• [x] * Zombie attack/eat?
• [x] * Zombie take damage?
• [x] * Zombie die?
• [ ] * Zombie spawn?
• [ ] * Plant take damage?
• [ ] * Plant die?
• [ ] * Plant spawn?
• [ ] * Sunflower spawn?
• [ ] * Sunflower die?
• [x] Sunflower spawns a sun
• [x] * Sunflower spawning sunshine?
• [ ] * Mower attack?

[david-campos]

I think zombie take damage would improve a lot the experience, so we should prioritize it.

EDIT: may be enough with hitting effect and no need for animation