automatic locations

Creates a command that generates locations object for locations with many entries. 
* Neighbor class takes an object with coordinates. Finds other objects with nearby coordinates.
* WebFinder finds uses the Neighbor class to find groups of entries (or any object with coordinates) that  are close to each other.
* CoordinateCenter finds the average latitude and longitude in those groups.
* Csv maker formats a file of world cities.
* LocationFinder takes the coordinate centers and the list of cities.  It finds cities that are near those centers.
* LocationBuilder builds new Active Record Locations for each city that Location Finder finds.
Yeah, the operation of the model requires that it be dealing with objects that have coordinates. If it's passed a collection of ids, I'd like to be able to convert it into a collection of objects.  Maybe I should just be passing in a collection of objects?