Add __repr__ and __str__ methods to registry.RegistryKey
Add __repr__ and __str__ methods to registry.RegistryKey

__repr__ in particular is necessary to produce a useful traceback when a
RegistryKey is passed as an arg to KeyError.

PSU-OIT-ARC/django-arcutils,wylee/django-arcutils,PSU-OIT-ARC/django-arcutils,wylee/django-arcutils