String and UI changes in gnome-system-tools

[Milan Bouchet-Valat <nalimilan club fr>]

Hi!

I'm both sorry and glad to announce you some changes have just landed in
the users-admin part of the gnome-system-tools. Glad because these
really were necessary additions, and because they are likely to be the
last breaks this cycle. Sorry, well, you know why!

To be more precise and helpful, these changes are:
- a dozen of new error messages about password authentication
- a new checkbox with its label and tooltip
- a new entry with its label

I don't think anybody will bother documentation-wise since anyway our
docs are sadly out of date since the beginning of the cycle for
users-admin - and it wasn't really helpful anyway. Maybe one of these
days I'll put myself to writing it in Mallard, maybe...

So good luck to translators, and thanks for your work!