When run with the '-f' flag to force handling of specific sections, only grab those sections from Canvas API
Add full support for only updating certain sections
 - This is meant for real-time updating of a particular section or sections that were
   created during the day and can't wait til the overnight update. It can also be
   used to fix errors or to forcefully empty a section (by default, the script will
   refuse to remove all enrolments even if the data source claims there shouldn't
   be any)

 - use the '-f' option followed by one or more sis_section_id's, separated by commas
   to specify which sections to update

 - The script only pulls data for the sections being updated and the users in those
   sections, so it should complete in seconds
Merge branch 'feature_one-course'