Use string.ascii_letters instead of string.letters in utils._generate_string to prevent the server from blowing up when locale is other than C.
Use string.ascii_letters instead of string.letters in utils._generate_string to prevent the server from blowing up when locale is other than C.

mstepniowski/django-cas-provider,mitocw/django-cas-provider,mitocw/django-cas-provider,Nitron/django-cas-provider