Option to automatically disable course after end date

[damianhxy]

Currently, courses that are past their end date are simply moved under a different header, from "current" to "completed".
To further prevent students from accessing these courses, the course must be further marked as "disabled".

It might be desirable to have a setting that will automatically disable courses that are past their end date, e.g. "Disable course on end date". This would deter cheating via students downloading their old submissions from Autolab.