Add method to Legislature that returns the path component of the names.csv URL

[ondenman]

The Legislature class should provide a method to return the path component of the URL of the names.csv file for the given legislature.

Example:

The download.erb template in view-sinatra accesses the URL from the raw data:house[:names].
(Example return value: data/Bosnia_and_Herzegovina/House_of_Representatives/names.csv)

It should be accessed like so: house.names

[tmtmtmtm]

I'm not so sure that house.names is the right name for this — I would expect that to return me a list of names, not a URL.

I'd probably make this names_url (cf: csv_url vs csv)