extend filtering capabilities to reviews-all and grades-all views

[rachelyeshurun]

I would like to see the grade breakdown for all courses, but only for certain semesters. For example, the last semester. Same for 'All Reviews'. For example, I wanted to order the courses by their average rating given in the past 2 semesters because I noticed from the written reviews that as courses run longer and become more organized, their rating improves sometimes dramatically, making the average rating a less helpful statistic.