Merge branch 'master' of https://github.com/TEAMMATES/repo into Issue1873
add test case to consider non-existent fs
added test cases to check the condition when no questions are there for the user
Merge branch 'master' of https://github.com/TEAMMATES/repo into Issue1873
Merge branch 'master' into Issue1873
[1873] Clean up InstructorFeedbackRemindAction

fixes #1873