LayerStyles / Appearance API
Hi, I'm trying to generate our color palette in sketch with react-sketchapp, from the documentation react-sketchapp supports Symbols and TextStyles, what about layer styles?

Example:
I can run the color palette example, but each element of the palette only has direct styles applied to it, I'd like to use layer styles like this 👇 
![image](https://user-images.githubusercontent.com/2165256/72164986-b7337280-3394-11ea-94c3-744fae60628a.png)

Any pointers would be appreciated, otherwise I guess I'll have to use sketch's low level api?
