[8] Show the nearest 20 points on a map. Includes SQL refactor.

@alanjosephwilliams, I switched things around a bit — take a look and see what you think.

Remaining TODOs:
- [ ] Get store names and addresses (instead of an error message) to display in info boxes. Pretty sure this is a matter of fixing that SQL query.

Available for preview at http://fureigh.github.io/ebt-near-me/ as of 9:36pm on August 21.