StudentCourseJoinActionTest Cleaned up:
1. removed direct access to StudentsDb and AccountsDb by using logic as facade
2. to get page and redirect result, changed to using methods from baseActionTest instead
3. improved code readability
minor changing for page result getting
missing ;
1.changed to using lower level function to increase testing speed
2.removed unnecessary libraries
[1955] StudentCourseJoinActionTest Cleaned up

fixes #1955