Add babel plugin for converting CSS to JSS

[DenisIzmaylov]

See example here:

• https://github.com/threepointone/glamor/blob/v3/packages/glamor-raw-css/src/babel.js
• https://github.com/threepointone/glamor/blob/v3/packages/babel-plugin-glamor/src/babel-hoist.js

[DenisIzmaylov]

Use it as an example:

• https://github.com/lttb/babel-plugin-prejss

Probably we could just integrate with it.