Oec 374, Update primary OEC script to pad CCNs and add columns

The primary OEC script lives within CalCentral code and generates CSV files. A secondary script - owned by Ops - then processes those CSVs. We plan to retire the secondary script and consolidate logic in primary.
@ctweney : I'm testing CCN padding by adding a 4-digit in Oec::FileReader then verifying fixtures/oec/courses.csv, etc. get the proper five-digit, padded version. Will that satisfy your request?