Constrain GUI to what the OS will allow. Fixes ticket 474
fix retrieve of users using json for empty exclude group
also vacuum the database after deleting django_session entries
migration to delete sessions from db
more accurate trans (thanks to Marion DESNAULT)
accept utf-8 user password and full name
set default cifs user to nobody; add the ability to exclude users
fix migration in case of noxexistent user
Add _plural to models
show email in the Add user form