GTFS Data Update Checker
This module runs the agency update checks. The agencies to check are set in the build options and are returned from the options module. Depending on the Agency settings, this will either run the default update function or the agency-specific update function.
If the agency has a post-update script defined, this will be run after the agency update script is complete, regardless if an update is requested.
Start the database update check process. This will check for a GTFS data update for all agencies specified in the Database Build Options (Options). If an update is present, the new data will be downloaded and unpacked into the agency's GTFS directory.
Final callback when the update process is complete.