Improve map rendering

[pnijjar]

This is an oldish issue but still needs work. We want to replace the map rendering done by default on GH pages with our own Leaflet that has better tuning:

• Street names should render on the map (right now it is very coarse)
• There should be an easy-to-use search field
• There should be messages saying that the map is loading, since rendering the map is slower than loading the home page
• The region should fit better in the map. It is too small in the default rendering.

[pnijjar]

@ToddTurnbull has a demo here: https://wr-votes-toddturnbull.c9users.io/search-map.html