Issue1896
InstructorFeedbackSubmitPageUiTest
+ Complete TODO: add grace period test case
Remove TODO in testModifyData - seems okay to be done as a UI test to check visibility of the response at html level.
Add test to check submit button is disabled when session is closed.
Merge branch 'master' into Issue1896
[1896] Clean up InstructorFeedbackSubmitPageUiTest

fixes #1896