add assumptions for FeedbackResponsesLogic
rename variable
Show status message to student when accessing deleted evaluation

Added a status message:
The evaluation has been deleted and is no longer accessible. Please
contact your instructors if you need to submit/edit an evaluation.
Changed status message
Added status messages to feedback sessions

Shows a status message to user when trying to edit a deleted feedback
session
Merge branch 'master' into Issue1936
add FeedbackResponseCommentsLogicTest, and make dev green
cover more branches
Clean up StudentCourseJoinAuthenticatedAction:
1. simple stuff to improve readability
2. changed to lower level methods to increase testing speed
3.spotted unreachable exception handling case, added a TODO for future logic and AccountLogic exception issue for method joinCourseForStudent
minor typoes fixed
//TODO simplified for unreachable branch
comma moved cosmetic reason
refactored verifications
make dev green
Add FeedbackQuestionsDbTest
Add helper function in TestHelper
Recreate instructor account if detected to be null
Merge branch 'master' into Issue1941
Clean up StudentFeedbackQuestionSubmissionEditPageAction:
1. moved unregistereduserToHome test into testExecuteAndPostProcess
2. "moved trying to access question not meant for the user "  into testAccessControl
3. Override verifyCannotAccess function for specific verification test
4.Improved code readability
5.added some verification tests
Added tests

Add a test for when instructor joining but account creation goes wrong
Add tests in FeedbackQuestionsDbTest
Add test to testing.xml