context missing in react-sketchapp 1.0.0-beta.* used with a Sketch plugin
Hey folks,

I was giving the latest beta version a try and figured out why it was breaking for us when used in a sketchapp plugin environment.

The main difference to the latest stable version is the use of `context` in some parts of the library as in
https://github.com/airbnb/react-sketchapp/blob/master/src/render.js#L133
https://github.com/airbnb/react-sketchapp/blob/master/src/resets.js#L16

I'm not 100% sure where the reference to a global context is coming from but I guess this is available when executing the `renderer` via `npm` on the CLI. How is it possible to share the context that's available in a sketch plugin script with the react-sketchapp `render()` call?

I've also noticed that with the 1.* branch pages are cleared out before rendering. Is that something that is supposed to stay in the final version?

I'd be grateful for some feedback as I'm preparing our application currently for the 1.0 release.

Thank's a lot.

Roland