Geolocation with postgis

Once we reach a larger amount of locks we want to be able to only fetch the ones near you. For this we can use a Postgres extension called [PostGis](http://postgis.refractions.net)

Here is a simple walkthrough on how to use it with rails: [PostGIS and Rails: A Simple Approach](http://ngauthier.com/2013/08/postgis-and-rails-a-simple-approach.html)