Rethink user management
With the nk20, it will no longer be necessary to have members in database, and it will be cleaner to remove them.
The global idea is to :
- Allow everyone to read games, media, authors (no login required) ;
- With a SAML or CAS (such as django-cas-server package from the Cr@ns) make user able to login with the nk20 or social account and register borrowed items.