apps.core.models.static_feedback: Removed feedback_grade_delete_handler.
apps.core.models.static_feedback: Removed feedback_grade_delete_handler.

This removed grade plugins, which we do not use anymore.

vegarang/devilry-django,devilry/devilry-django,vegarang/devilry-django,devilry/devilry-django,devilry/devilry-django,devilry/devilry-django