Modify some layout
Check if user is student or teacher. If invalid role, auto logout and require login againModify some layout
Modify layout view lesson
Merge branch 'master' of https://github.com/giapnh/T08_E-learning

Conflicts:
	Elearning/application/modules/default/controllers/TeacherController.php
Merge branch 'master' of https://github.com/giapnh/T08_E-learning
Merge branch 'master' of https://github.com/giapnh/T08_E-learning

Conflicts:
	Elearning/application/modules/default/controllers/TeacherController.php