fix instructor course permissions checking spilling over to clientFiles; close #491
fix instructor course permissions checking spilling over to clientFiles; close #491

parasgithub/PrairieLearn,tbretl/PrairieLearn,kevinwang/PrairieLearn,kevinwang/PrairieLearn,tbretl/PrairieLearn,tbretl/PrairieLearn,rbessick5/PrairieLearn,parasgithub/PrairieLearn,jakebailey/PrairieLearn,tbretl/PrairieLearn,mwest1066/PrairieLearn,parasgithub/PrairieLearn,kevinwang/PrairieLearn,mwest1066/PrairieLearn,PrairieLearn/PrairieLearnHack,PrairieLearn/PrairieLearnHack,kevinwang/PrairieLearn,jakebailey/PrairieLearn,rbessick5/PrairieLearn,rbessick5/PrairieLearn,kevinwang/PrairieLearn,parasgithub/PrairieLearn,mwest1066/PrairieLearn,PrairieLearn/PrairieLearnHack,lotrfan/PrairieLearn,kevinwang/PrairieLearn,mwest1066/PrairieLearn,lotrfan/PrairieLearn,PrairieLearn/PrairieLearnHack,parasgithub/PrairieLearn,rbessick5/PrairieLearn,rbessick5/PrairieLearn,lotrfan/PrairieLearn,tbretl/PrairieLearn,jakebailey/PrairieLearn,PrairieLearn/PrairieLearnHack,kevinwang/PrairieLearn,PrairieLearn/PrairieLearnHack,mwest1066/PrairieLearn,lotrfan/PrairieLearn,PrairieLearn/PrairieLearnHack,lotrfan/PrairieLearn,jakebailey/PrairieLearn,lotrfan/PrairieLearn,lotrfan/PrairieLearn,PrairieLearn/PrairieLearnHack