Add polling place data

[emlabor]

Polling places have changed due to COVID-19, but the public data set was last updated in 2017. Polling place data is available here but I haven't been able to figure out what this page is querying. May just ask the clerk's office.

[emlabor]

2017 data added with commit 1384c2b. This means the popup will eventually be dependent on two asynchronous functions, one of which depends on the other. Not sure how to handle this yet.