Fix ActiveRecord all deprecation by replacing it with to_a

Since `all` is deprecated in Rails 4, I used `to_a` instead. Asserting equality of `locations.to_a.size` and `locations.count` feels a bit redundant though. What do you think about removing the `to_a.size` checks?

Also -- tests are passing (and others aren't throwing warnings) once we stop using this deprecated method


My other commit removes a test of `sort_by_distance_from` because that method is deprecated in Rails 4.