Webpack

Make building static assets for front end easier by automating all the things and splitting them up

- webpack
- gulp
- split into `priv/ui/app` for source and `priv/ui/public` for actual files for running static app
Based on [a talk](http://ryanseddon.github.io/stupid_things_with_checked-talk/talk/) at MelbCSS this week, we should be able to iOS7-switchify some plain old checkboxes with CSS pretty easily rather than needing Switchery. Could be a hassle if React starts adding new elements to the DOM after this has run, you'd need to re-run switchery after render.