RFC: Service Workers

[delambo]

Investigate the various webpack service worker plugins and sw-cache/toolbox and create an RFC for Service Workers in kyt.

I'm going to assign this to myself because we will need some internal work to test this against our apps, but feel free to do your own investigation and POC. I'd like a good, flexible implementation.

[janhoogeveen]

This should help: https://github.com/jeffposnick/create-react-pwa#adding-in-a-service-worker

[janhoogeveen]

We made a beginning on this spike in our own fork.

All static assets are cached properly. All that remains is making sure the routes themselves are cached as well, otherwise reloading while offline is still impossible.

[felipesilva]

Issues found on create-react-app while integrating SW https://github.com/facebookincubator/create-react-app/issues/2554