1.implement adminAccountDeleteActionTest
2.add status message test
1.implement adminAccountDetailsPageActionTest
2.add status message test for this
1.implement adminAccountManagementPageActionTest
2.add status message test for this
1.add status test for some action test
2.remove TODO for tests that already have status test
3.implement some test which were previously empty
4.fix instructorHomePageUiTest by adding mission "restoreTestDataOnServer(testData)" command
Merge pull request #2225 from TEAMMATES/Issue2119

Test status message in actionTest #2119