Further clean up of remote XML docs when harvesting

Some old forms of BOM were giving trouble, eg in

http://certmapper.cr.usgs.gov/data_gov/oilgas/noga00/National%20Assessment%20of%20Oil%20and%20Gas%20Project%20%20Bend%20Arch-Fort%20Worth%20Basin%20Province%20(045)%20Boundary.xml