Animated.loop  is not working in web

Hey there. Animated.loop is not working when I start the animation in web app. the problem is in the useNativeDriver: true
Seems need to add a condition there to be like:
```
useNativeDriver: Platform.OS !== 'web',
```

https://github.com/MiLeung/rn-sprite-sheet/blob/master/src/SpriteSheet.js#L213

