fix system_role to role conversion in users.rb
fix system_role to role conversion in users.rb

doubtfire-lms/doubtfire-api,alexcu/doubtfire-api,final-year-project/doubtfire-api,doubtfire-lms/doubtfire-api,doubtfire-lms/doubtfire-api,alexcu/doubtfire-api,jakerenzella/doubtfire-api,final-year-project/doubtfire-api,doubtfire-lms/doubtfire-api,final-year-project/doubtfire-api,doubtfire-lms/doubtfire-api,doubtfire-lms/doubtfire-api,doubtfire-lms/doubtfire-api,jakerenzella/doubtfire-api,jakerenzella/doubtfire-api,final-year-project/doubtfire-api,jakerenzella/doubtfire-api,jakerenzella/doubtfire-api,alexcu/doubtfire-api,alexcu/doubtfire-api,alexcu/doubtfire-api,final-year-project/doubtfire-api,alexcu/doubtfire-api,jakerenzella/doubtfire-api,jakerenzella/doubtfire-api