Assign always the same ip

[zamentur]

I wan't to be able to assign a fixed ip to each yunohost/ldap user.

May be with a handler.sh script https://github.com/YunoHost-Apps/openvpn_ynh/pull/20/files#diff-070a23f3efab8f6df4f29a18e34e638aR71

or with the access hooks.