(WIP) asadiqbal08/enable entrance exam checkbox under requirments section

@mattdrayer kindly look into the change set and share your feedback. 

- added 'enable entrance exam' section under requirements. 

@ziafazal 
Thanks
@asadiqbal08 -- looking at this again -- if you review the parent branch (mattdrayer/entrance-exams) you will see a metadata field on the course 'entrance_exam_enabled' (course_module.py, line ~665) -- we should set/use this field instead of 'is_entrance_exam' to avoid confusion with the 'is_entrance_exam' metadata field on the sequence module (see seq_module.py, line ~50)