"Comparing Fractions 1" now grades the "Same numerator" problem type correctly

Summary: "Comparing Fractions 1" was grading "Same numerator" based on the numerator
values, which were always equal (so the answer was always the same). Now, it grades
based on the denominator.

Test Plan:
- Did a bunch of "Comparing Fractions 1" items.
- Everything graded correctly!

Auditors: jack, eater