automatic locations

Creates a command that generates locations object for locations with many entries. 
Does this with 6 models:
 * EntryWeb takes an entry and finds entries with close coordinates
 * NetworkCenter evaluates a web of entries and finds the ones that are central (that have the most nearby entries)
 * NetWorkCenter is helped by a NestedHashConverter which converts hashes of objects into hashes of coordinates
 * DataParser takes a text file with the name of every city, it cleans it, and makes it into a list of city names and coordinates.
 * LocationMaker uses the NetworkCenter to find coordinates in the center of entry density.  It uses CityNameSearcher to find the names of cities near those coordinates.  Then it generates Location objects for those cities.
Unused method argument - `rows`. If it's necessary, use `_` or `_rows` as an argument name to indicate that it won't be used. You can also write as `nested_coordinate_hash(*)` if you want the method to accept any arguments but don't care about them.