Add dump.rdb to gitignore
Configure Geocoder to use Mapquest, and cache results in Redis

We were hitting the 2500 requests/day limit with the Google Maps API, so we're switching to Mapquest, which doesn't have any limits. I've also configured Geocoder to cache results with Redis, which improves performance considerably.

The README has been updated with Redis installation instructions.

Unrelated changes:
I added more fields to the model in anticipation of the CIP data.
Adds fallback for icons to unicode

Webfont icons were mapping to arbitrary letters, this commit maps them
to unicode characters that correspond to what they represent so that
users that don't support the @font-face rule will still see icons and
screenreaders will (hopefully) be given more semantically sound results
when parsing over the icons.
Updates webfont for unicode fallback

Webfont mappings are now linked to similar unicode characters instead
of arbitrary letters.
Merge pull request #76 from codeforamerica/icon-fallback

Icon fallback
Update README formatting
Merge branch 'master' into details-formatting
Fixes incorrect value check

Services overview section was checking if payments or products were
present for an entry, it should check if the description is present.