Fixed showing the correct list of projects for taking a Grading Project Survey. Note that when a user is a mentor for a lot of Organizations the amount of subqueries might exceed the allowed amount. A TODO has been added to fix this issue. However this will hopefully not be a problem that pops up soon. Also some minor docstring addition to Project Survey view.

# Primary owners
arb
bslatkin
guido

# Backup
kgibbs