refactor InstructorFeedbackUnpublishAction
adding code for todo and improve test

trim; test: confirming comments and student email team edited and saved
fixing of the issue and test passed

test passed, the added test code is to test trim function and parts
following it are not influenced
fixing of the test fail

should be all passing now
Merge remote-tracking branch 'origin/master' into Issue1808
refactoring of test

InstructorCourseStudentDetailsEditPageUiTest: refactored unclean code
Merge branch 'master' of https://github.com/TEAMMATES/repo into Issue1806
clean up InstructorFeedbackUnpublishActionTest.java
marking for later reference

no test code added -- not adding duplicate tests; main part is tested in
logic already
Revert "marking for later reference"

This reverts commit 15281f0b3fb0518be75885fa2ce8eb00eb5d4a6e.
add marking for later reference

the content is tested in LogicTest; file name can be passed
Clean up InstructorCourseAddAction class
Mentioned 'GitHub flow' in the process.md
Merge remote-tracking branch 'origin/master' into Issue-1809
Mentioned 'GitHub flow' in the process.md
Merge branch 'master' of https://github.com/TEAMMATES/repo into Issue1806
change upon requests

refactored files. one more to go
Revert "clean up InstructorFeedbackUnpublishActionTest.java"

This reverts commit 13e34031b3958aa984e2e50bfd26d10c573a8d95.
for unpublishActionTest, I only test success and failure (due to accessibility). Other failure due to logic will be tested in the logic test
remove magic number in UnpublishActionTest