Should be able to mark an activity complete based on a specific grade, not just any grade

Currently activities can be set so that they are considered 'complete' once the user has been assigned a grade.

It would be helpful to have a further option to allow them to be considered 'complete' once the user has achieved a specific grade (e.g. 80% or greater). This feature is already available when specifying conditional activities, but not when specifying completion of an activity.