Make it easier to get directions on the detail page

[jimthoburn]

The detail pages have a map with the food source’s location, and a link a full-screen map page with directions (Google Maps).

We could make the map into a giant button that goes to the same place.

Or we could change the map on the page to include directions. Mapbox has an API that may help:
https://www.mapbox.com/api-documentation/#retrieve-directions

Bonus points: Consider using “Mapbox classic” instead of “Mapbox GL” on the detail page, to make it consistent with the locations page: https://foodoasis.la/locations/?address=San+Gabriel