naming rules allow to support case insensitive usernames, trim trailing
and leading white spaces, and accept any valid UTF-8 characters in
usernames.
If you were enabling `skip_natural_keys_validation` now you need to
set `naming_rules` to `1`
Fixes#687
Signed-off-by: Nicola Murino <nicola.murino@gmail.com>
02db00d008