[Bug 827650] Add localization support to AAQ

Of note:

* Minor update of elasticutils, since the old version couldn't filter by `None`.
* Tests that work with AAQ need to have locales in the DB now.
* AAQ Is enabled for pt-BR, en-US, and xx.
* While testing: the xx locale won't have any KB article or questions, but other locales won't have any updated strings, so you should look at both xx and pt-BR.
* Use `./scripts/test_locales.sh` to generate the xx locale. (Thanks @willkg!)

I think that's all the interesting bits.

r?