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
May want to add `private: true` http://stackoverflow.com/questions/7314849/what-is-purpose-of-the-property-private-in-package-json . I am assuming the front-end part of iodized is useless without the Elixir backend and would be a bit pointless to if published as its own npm package.