[Calendar] Calendar Appointment - Enable 24 hour appointment requirement

[kmillerumass]

Problem statement:

Students are currently able to sign up for appointments one minute before the appointment time begins. This is a problem because it's difficult to schedule time when we don't know if students are coming to office hours until right before the time slow begins.

Proposed solution:

Create an option in the calendar that allows faculty to set a required time for how students can sign up for time slots. For example, empty slots would close 24 hours ahead of the appointment (or 12 hours or four hours).

User role(s):

instructor