Bug 425145 adds an about:config option, `signon.overrideAutocomplete`, which when set to true allows the password manager to save passwords for pages where the form/form elements have `autocomplete=false`. Can/should this be exposed in the preferences?

Preliminary patch (requires https://bug425145.bugzilla.mozilla.org/attachment.cgi?id=8349839). I have kept it in the Security tab along with the rest of the password options. I have't yet added it to in-content, but that can be easily done. Currently, the option is not disabled if Save Passwords is unticked (because most of the other password options are not disabled either). Of course, we must first answer the question: Should this pref be exposed in the first place?

I filed bug 956906 to do something like this by default, which might remove the need for this pref.

We're going to WONTFIX this in favor of bug 956906, I think.