Add button to notify student that they couldn't be located

[andyclee]

Though not exactly common it happens often enough where I will go to help a student and they won't be at their stated location. Usually this has been because they were in the wrong lab room or went to use the bathroom but there isn't much I can do right now except ignore them and check back whenever there's a lull which for busy days usually means I just won't ever get back to them. An option for notifying students that they couldn't be found and forcing them to the end of the queue would be helpful.

[Yashub]

might also help to be able to add a note