Add support for fade at the top of the container

[ahanriat]

HI,

It's currently not possible to add the fade effect to both the top and the bottom of the container (or maybe I'm missing something?)

Would you like me to open a PR to add this functionnality?

I would add a props to the ScrollFade component to enable both top and bottom fade.

Let me know what you think

[masciugo]

@ahanriat did you find a solution? Are you still using this library? Thank you