Courses: exams, surveys loading bug

[jessewashburn]

I throttled to 3g to test loading and found that in exams and surveys, the header updates before the test question when navigating via the arrows.

Also, I see a loading screen when navigating forward via the arrows (goes away when the header loads), but not when navigating back.

exams_surveys_loading.webm

[RheuX]

i think the headers updating is fine, since the loader doesn't let them do anything, but i do agree we should have a loading spinner when navigating backwards