Gather data on recreational public spaces and extract features

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I also spoke with Jason tonight about adding data for recreational public spaces like parks or fields.

More notes:

Research article showing association between recreational public space and rodent sightings: https://peerj.com/articles/533.pdf

Properties under the jurisdiction of the DC Department of Parks and Recreation (with possible other variables of interest like VSTRSHCAN and PICNIC): http://opendata.dc.gov/datasets/287eaa2ecbff4d699762bbc6795ffdca_9

Other datasets may be relevant as well.