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
Clean up InstructorCourseAddAction class
Mentioned 'GitHub flow' in the process.md
Merge remote-tracking branch 'origin/master' into Issue-1809
change upon requests

refactored files. one more to go
Remove redundant comments
Change variable name to be more meaningful
Remove redundant comments to distinguish between course detail and summary
Format and delete comments
Issue 1807
InstructorFeedbackQuestionAddAction
- It is currently possible to add questions with empty question text by modifying the js validator script.(instructorFeedback.js:64)

+ Added assumption to FeedbackAbstractQuestionDetails to assume questionText not empty.
+ Added test for empty questionText, expect assumption faliure.
+ Added test for non-existent enumerations of giver/recipient/question type, expect assumption faliure.
+ Added test for invalid questionNUmber
Remove catching and defining EntityDoesNotExistException since it is never thrown/not possible to be thrown by any method related.
Remove EntityDoesNotExistException since it is already caught by  function createFeedbackQuestion().
Added Assumption.assertNotEmpty/IsEmpty for String. Changed such assertions across TEAMMATES to use the functions.
undo some wrong changes
Added a modifyParamValue() function to make code in test/cases/ui/InstructorFeedbackQuestionAddActionTest.java clearer.
Added a TODO in FeedbackAbstractQuestionDetails to add a validate function.
Merge remote-tracking branch 'origin/master' into Issue1808