Loading fails on files which contain a UTF-8 Byte Order Marker

Some feeds start with a BOM, which is allowable per the GTFS spec. For example, http://gtfs.s3.amazonaws.com/addison-county-transit-resources_20150227_0141.zip, stops.txt, starts with a BOM.

Attempting to load this feed causes an exception:

UnicodeEncodeError: 'ascii' codec can't encode character u'\ufeff' in position 0: ordinal not in range(128)
