Make sure CSV data can be parsed if headers are not consistent

[romanofski]

Some of the data we find out there does not include headers and data for optional fields (e.g. the Brisbane CSV data misses https://developers.google.com/transit/gtfs/reference/stop_times-file shape_dist_traveled from the reference). Investigate if we can import the data if the dataset provides these optional fields, although no functionality is using it right now.