Create basic build setup

[chrisdmacrae]

This is a base build config that will handle creating a PWS (progressive website).

This should all be implemented as generic helpers that are glued together in the general config. This will help people build their own pipelines!

• [ ] Webpack
  • [ ] Runtime Code splitting
  • [ ] ES6
  • [ ] Optional typescript
  • [ ] Babel
  • [ ] Service worker generation
  • [ ] Web app manifest (generation?)
• [ ] PostCSS
  • [ ] Autoprefixer
  • [ ] Laggard
  • [ ] CSSNano
  • [ ] CSSNext
• [ ] Jest (or something) testing
  • [ ] Unit testing custom JS
  • [ ] Testing the built site
  • [ ] Screenshot regression testing (post-build)
• [ ] Dev server (browsersync)
• [ ] Allow for custom tooling?