Was causing an error when deploying on Heroku ("production database is
not configured").

Instead use an array for key, client, and channel.

Thanks github.com/hairyheron.

Add example to README on retrieving coordinates from mongodb model.

Fixes issue #75 (ActiveRecord) and more (Mongoid).

Prevent an exception when geocoding is initialized for
a child STI model when the parent is also geocoded.

In certain conditions a lookup returned [nil] instead of [], which
caused a Result object to be initialized with no data.