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
clean up InsFbResponseCommentDeleteAction
Issue1863
FeedbackSubmissionEditPageAction

+ Add test case closed session
+ Remove unnecessary conditional to check for null and throw exception since it will already be thrown by getDataBundle function.
+ Refactor some confusing code
Remove unused variable
Some refactoring of confusing code
clean up insFbResponseCommentEditAction
Clean up InstructorCourseInstructorEditSaveAction
Refactor and add missing test cases for updating instructor in InstructorsDb
Refactor and modify test cases to be more detailed
Clean up InsFbResultsPageUiTest
[1886] Clean up InstructorFeedbackResponseCommentDeleteAction

fixes #1886
Merge branch 'master' into Issue1888
[1888] Clean up InstructorFeedbackResponseCommentEditAction

fixes #1888
Merge branch 'master' into Issue1863
[1863] Cleanup FeedbackSubmissionEditPageAction

fixes #1863
Merge branch 'master' into Issue1873
[1873] Clean up InstructorFeedbackRemindAction

fixes #1873
Merge branch 'master' into Issue1884