374-RI-Legislator URL

Legislators are parsed from an XLS document for Rhode Island. Rather than having the XLS document URL as the source_url for all legislators someone suggested in [issue 374](http://code.google.com/p/openstates/issues/detail?id=374) their corresponding house/senate URL be used. If a legislators name from the XLS document matches a name from the house/senate list on RI's site, that URL is used instead.