Re-add nbgrader script
Re-add nbgrader script

ellisonbg/nbgrader,jupyter/nbgrader,EdwardJKim/nbgrader,jupyter/nbgrader,jhamrick/nbgrader,jhamrick/nbgrader,ellisonbg/nbgrader,jupyter/nbgrader,EdwardJKim/nbgrader,EdwardJKim/nbgrader,EdwardJKim/nbgrader,ellisonbg/nbgrader,jupyter/nbgrader,jhamrick/nbgrader,jupyter/nbgrader,jhamrick/nbgrader,ellisonbg/nbgrader