Deleted TimeSlot class(as it was kind of useless, repeated info in Session class) and updated Week and Day to reflect change
Fixed relationships between User, Tutor, Admin, Student and Lecturer.
Also removed/commented redundant code
Forgot to commit Student class(oops)
Added courseID to course class
Fixed Merge Conflicts
removed Timeslot reference
Fixed formatting
Added session add method and changed timetable to a singleton