Group edit now works like it must work =)
 Changes to be committed:
	modified:   ext-resources/DB_FILL.sql
	modified:   school-dao/src/main/java/school/dao/implementation/StudentDaoImpl.java
	modified:   school-dao/src/main/java/school/dto/GroupEditResponseDTO.java
	modified:   school-dao/src/main/java/school/dto/StudentDTO.java
	modified:   school-service/src/main/java/school/service/GroupService.java
	modified:   school-service/src/main/java/school/service/implementation/GroupServiceImpl.java
	modified:   school-web/src/main/java/school/controller/GroupEditController.java
	modified:   school-web/src/main/webapp/resources/js/group-edit.js