Add ability to make a "built" version of Finda

Resulting tree:
```
dist
├── config.json
├── data.geojson
├── index.html
├── lib
│   └── leaflet
│       └── images
│           ├── marker-icon-2x.png
│           ├── marker-icon-gray.png
│           ├── marker-icon.png
│           └── marker-shadow.png
├── license.md
├── readme.md
├── src
│   └── finda.min.js
└── styles
    ├── properties.css
    └── style.min.css
```

I'm not a huge fan of the `lib/leaflet/images` path but it's easier to leave those paths alone.

Closes #48