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
Could pass a callback into `FeatureForm` from `FeatureBox` that calls `setState` and lets this be handled in `FeatureBox.render` rather than manually fiddling with the DOM

```
// right here
this.props.handleSaveFeature()

// up in FeatureBox
handleSaveFeature: function () {
  this.setState({expanded: false});
},
render: function () {
  var expandedStateClass = this.state.expanded ? "is-expanded" : "is-collapsed";
  return(
    <div className="new-feature {expandedStateClass"}">
      // etc etc
      <FeatureForm ref="featureForm" handleSaveFeature={this.handleSaveFeature}/>
    </div>
  );
}
```