Add user password-syntax-check

[gdav]

Hello,
I'm now testing the RC1.
I'm very glad about you're work,
it's realy great and the new features are fantastic!

But when I'm creating a new User as user in the "group - usermanagement" and I want only an numeric password, I get an Error like "Incorrect password range or syntax!".
I know, that an only numeric password isn't secure, but I would be great, that the error says exactly, that no only numeric passwords are allowd,
because of "stupid" clients.

^^I see many Tickets because of this fact

greeting gdav