Revert "add User.backend field set in django 1.3"
Revert "add User.backend field set in django 1.3"

This reverts commit 7bab5e5dd412e647cd35de0dd93b9f95ba0faffb.

stefankoegl/django-couchdb-utils,stefankoegl/django-couchdb-utils,stefankoegl/django-couchdb-utils