Add simplestyle-js as an additional zero-dependency library option

[benduran]

Hi there!

I'm the author of simplestyle-js, and I've been using this library in a production application at work with good success. The library's creation was motivated by trying to reduce dependencies and bundle sizes, as well as having a super straight forward CSS-in-JS solution that doesn't make too many assumptions about your styles.

I can issue a PR against this repo to add this as an option, or, if you have time, you can take a look and add it as an option as well. Let me know if you have any questions. Thanks!!

[dustinboston]

This library is the future. It's awesome because you don't have to download half of the internet to use it. It really is simple and it Just Works. (full disclosure, I have been giving tiny bits of input on this library during its development so I am a probably a little biased).