nerdEd/gtfs — pull request #6 by s2t2 (2012-12-18 02:24:10+00:00)
Title: Calendar file name expectation

The Calendar class was looking for the wrong filename, and was throwing this error upon attempts to access source.calendars:

+ GTFS::InvalidSourceException: Missing required source file: calendars.txt

So I un-pluralized the filename expected by the Calendar class to match the [gtfs specs](https://developers.google.com/transit/gtfs/reference#calendar_fields).