[New Endpoint] Instructor and coordinator comment

[Taekwonnie]

We'll need a set/get endpoint to save the instructor and coordinator comment for each section.

Something like this:

GetInstructorComment(term,year,department,courseNum,sectionNum){return string}
SetInstructorComment(term,year,department,courseNum,sectionNum,String comment)

GetCoordinatorComment(term,year,department,courseNum,sectionNum){return string}
SetCoordinatorComment(term,year,department,courseNum,sectionNum,String comment)