Adds interactivity to map thanks to the excellent example at http://bl.ocks.org/mbostock/2206340
Visual improvements.

- Requires Google Chrome.
- Positions map in center screen.
- Click map to zoom and center.
- Positions graph in center above screen.
- TODO: Unroll/rollup the drawer.
- TODO: Click map to asynchronously load data point and unroll the drawer.
- Applies simple color scheme from http://flatuicolors.com.
- Applies brand typeface 'Montserrat' via Google Fonts.
- Applied brand icon 'Drop' by Julien Deveaux (CC-BY 3.0) via the Noun Project.