reorganization

I'm not sure if you'll want this one, but here it is just in case. I reorganized the gem, put all the endpoints under the Endpoint namespace and created three main objects:

geo_box: a box with north south east west. 
geo_place: place with geoname_id
geo_point: point with lat lng

each of these objects has methods for all the endpoints that take their attributes as arguments.

Since this somewhat rewrites the way the gem is used, I'll leave it up to you if you want to adopt this style or not. Another option for backwards compatibility is to add these new objects without moving the original endpoint objects into a new namespace, but things start to get cluttered.