added test cases for better coverage. changed method name to clarify its function
Merge branch 'master' of https://github.com/TEAMMATES/repo into Issue1954
Add FeedbackResponsesDbTest
Add missing assumption in FeedbackResponsesDb
Add helper functions in TestHelper
Change "assertEquals(null,... " to assertNull(..." in TestHelper
Fix typo
Add testGetFeedbackResponsesForQuestion
Add testGetFeedbackResponsesForSession
Add testGetFeedbackResponsesForReceiverForQuestion
Add testGetFeedbackResponseForReceiverForCourse
removed redundant FeedbackSessionType
Add testGetFeedbackResponsesFromGiverForQuestion
Add testGetFeedbackResponsesFromGiverForCourse
added test cases to expand coverage

-> email task queue related test cases are in
FeedbackSessionEmailTaskQueueTest.java
added a TODO to remove an unused function
Merge branch 'master' of https://github.com/TEAMMATES/repo into Issue1954
Add testUpdateFeedbackResponse
Add test to testing.xml
Merge branch 'master' into Issue1970
Add testGetNonPrivateFeedbackSessions
Add testGetFeedbackSessionsWithUnsentOpenEmail
Add testGetFeedbackSessionsWithUnsentPublishedEmail
Grouped getFeedbackSessions... tests for faster testing.
[1970] Clean up FeedbackResponsesDbTest

fixes #1970
Rewrote comments for better clarity