Merge branch 'task-implementation-course' into 'master'

.../java/id/ac/ui/tutorial0/controller/CourseController.java

...java/id/ac/ui/tutorial0/controller/StudentController.java

...ui/tutorial0/exception/DuplicateStudentNameException.java

src/main/java/id/ac/ui/tutorial0/model/Course.java

src/main/java/id/ac/ui/tutorial0/model/Student.java

.../java/id/ac/ui/tutorial0/repository/CourseRepository.java

...java/id/ac/ui/tutorial0/repository/StudentRepository.java

src/main/java/id/ac/ui/tutorial0/service/CourseService.java

...in/java/id/ac/ui/tutorial0/service/CourseServiceImpl.java

src/main/java/id/ac/ui/tutorial0/service/StudentService.java

...n/java/id/ac/ui/tutorial0/service/StudentServiceImpl.java

src/main/resources/templates/courseList.html

src/main/resources/templates/createCourse.html

src/main/resources/templates/createStudent.html

src/main/resources/templates/studentList.html