Added validation logic for adding and updating appointments. Refined get calls. Fixed exception handling. This is should be more or less stable (albeit beta) version of appointment logic.
Merge branch 'master' of https://github.com/joubin/CSC191

Conflicts:
	backend/src/main/java/com/teamsierra/csc191/api/model/User.java

Removed conflicting lines (added by me for dev). AppointmentController is more or less a stable piece of code. Added validations to creating and updating appointments. Refined AppointmentRepository custom search method.