Determine a design for the permissions model

There two possible ways of implementing the permissions model. One way would be to hardcode the permissions as predefined "Roles", and assign each User a Role for each exam that they're part of. Another possible solution is to have individual permissions for users per exam. An exam owner may give one grader permission to access the Students feature, and another grader permission to access all features. Currently (from the meeting yesterday), the latter appears to be preferable.