adds districts outline to home page

Currently we show a basic map on the home page, and only after the user picks a location (by entering address and clicking submit button or by dragging the marker) do we show the districts. 

It seems like the district outlines would be somewhat useful on the map on the home page (mainly for staff or city councilmembers who know what district they're interested in). The outline is light enough that it shouldn't be distracting to people who don't know what the shapes represent.