** Removed one to many references to course users and students from
Course entity
** Changed CourseUserRole into enum
** Added new entity CourseStaffMember that represents old CourseUser
** Changed CourseUser to be superclass of CourseStudent and
CourseStaffMember
** Removed getUnits method from GradeCourseResource and
StudentCourseResource entities
** Added CourseStaffMemberDAO
** Changed created CourseStudents to be automatically assigned into
STUDENT role
** Removed operations beloning to another entities from CourseUserDAO
(create, update, delete)
** Changed WebServices to use CourseStaffMember entity instead of
CourseUser entity
** Removed CourseUserRoleDAO as deprecated
** Added a old course role -> new course role mapping into WebServices
createCourseUser method
** Fixed view controllers to compile (they do not work yet though)
** Removed unused imports
** Added missing foreign key from Student (id) -> User (id)
** Added updater script that converts course students and users into new
table layout
** Replaced CourseUserRole enum with CourseStaffMemberRole entity
(equivalent for CourseUserRole entity) and moved it into
CourseStaffMember entity
** Added rest model entities for course staff members, course staff
member roles, course optionalities and course students
** Added mappers for new rest model entities
** Added methods for creating, updating, retriving and deleting course
staff member roles into CourseController
** Updated test sql scripts to match new database layout
** Added crud end-points for course staff member roles into course rest
service and basic tests for them