Proposition of overlay explockout

Hello,

I'd like to point out a new overlay that I wrote: https://github.com/davidcoutadeur/explockout

The aim is to require the user to wait for an exponential time before he can authenticate again, after some failed authentications. The overlay is quite simple: it relies on ppolicy for adding pwdFailureTime attribute and compute the time the user has to wait.

Maybe some of you can consider it useful. Please anyone feel free to give your opinion, comments or improvements. Also if OpenLDAP team is interested, I would be glad to have it incorporated in official OpenLDAP contrib modules.

David