bug: translation and promises for passport-local-mongoose
we need to add the ability to pass a phrase/locale to get translated by [passport-local-mongoose][] error handling.

this package is currently used at <https://github.com/ladjs/lad/blob/661333d37bf869072c73245fa716529c782c0a7a/template/app/models/user.js#L120> with configuration options at <https://github.com/ladjs/lad/blob/661333d37bf869072c73245fa716529c782c0a7a/template/config/index.js#L222>

furthermore, [passport-local-mongoose][] should be using promises instead of callbacks.

there are two issues right now filed that need resolved in order for Lad to support i18n translation for authentication error messages:

- [ ] https://github.com/saintedlama/passport-local-mongoose/issues/218
- [ ] https://github.com/saintedlama/passport-local-mongoose/issues/166

[passport-local-mongoose]: https://github.com/saintedlama/passport-local-mongoose