Hide Rankings in Assignments for students

Further to my discussion with Isaac, I would like to suggest that we have the option to turn off the visibility of rankings for students. We prefer our student to focus on their own improvement rather than compare their progress with the rest of class. We find little value in students comparing themselves against the class rather than against their own progress and the expectations of the institution. We still want students to be able to have their grades visible so would like separate grades from ranking.