Convert to topojson

The [raw geojson file](https://raw.github.com/benbalter/districts/master/hb259.geojson) is larger that GitHub's blob-view limit. Convert to [Topojson](https://github.com/mbostock/topojson) which can compress up to 80%.

[Rendered](https://github.com/benbalter/districts/blob/topojson/hb259.topojson)

![screen shot 2013-06-27 at 5 36 18 pm](https://f.cloud.github.com/assets/282759/718953/9efe051e-df71-11e2-864b-f1d43f2d879c.png)

/cc @dwillis because [Twitter](https://twitter.com/derekwillis/status/350366414525313024)