[mod:ctp,php] Modify the Student registeration view.

Modify the student registratio view by modifying register.ctp file
also small modifications to AppController and StudentsController.
[add:ctp] Add Student Registration Aprroval view ti the project

Add approve_student.ctp that contains the Student Approval view to
 the project. Also added 4 Elements that include alert messages. Modify
 StudentsController.php to add methods for newly added views.