Add a php script file get_score.php which can be run by professor to get the scores for a particular course

[sidharthkmishra]

Manual testing:

1. Login to cheshire.cse.buffalo.edu server
2. Go to /web/CSE442-542/2019-Summer/cse-442a/backend
3. Run the command: php get_score.php
4. You should get output like :

student_email_id,evaluation_submitted_by,role,leadership,participation,professionalism,quality,normalized_score kuduvago@buffalo.edu,smishra9@buffalo.edu,3,2,2,1,3,0.34375 c@buffalo.edu,smishra9@buffalo.edu,3,2,1,0,2,0.25 d@buffalo.edu,smishra9@buffalo.edu,3,0,0,1,2,0.1875 smishra9@buffalo.edu,smishra9@buffalo.edu,3,1,2,0,1,0.21875