map the precincts with census data

[smcalilly]

a map of the state, with a dropdown to choose county.

show the county, with voting precinct boundaries, polling locations, and demographics. should be able to show the different years on the map. v2 should be able to compare years with two maps.

todo:

• a basic map that can query the precincts based on the county and year
• add polling locations to that map
• add demographics to the map