Convert with properties

When converting to topojson, per the [command line instructions](https://github.com/mbostock/topojson/wiki/Command-Line-Reference), pass the `-p` flag to preserve properties. This will allow it to support identify on click.

![screen shot 2013-06-27 at 6 04 12 pm](https://f.cloud.github.com/assets/282759/719081/85856416-df75-11e2-83f0-5419ed2f2d0d.png)