Added try/except block for if a csv file is not given to addUsersFromList.py
Added try/except block for if a csv file is not given to addUsersFromList.py

noellekimiko/HMC-Grader,noellekimiko/HMC-Grader,noellekimiko/HMC-Grader,CSGreater-Developers/HMC-Grader,CSGreater-Developers/HMC-Grader,noellekimiko/HMC-Grader,CSGreater-Developers/HMC-Grader,CSGreater-Developers/HMC-Grader,CSGreater-Developers/HMC-Grader,noellekimiko/HMC-Grader,noellekimiko/HMC-Grader