(Bug 4909) Make sure to load _config-local.bml

Slightly weird behavior in terms of strings, including FAQs, because we
had a default language of en instead of en_DW (latter includes
everything that's live on the site, instead of just the repo). Reason
behind *that* is that we weren't loading the site-specific
_config-local.bml

So load it.
Merge pull request #292 from afuna/default-lang-bug4909

(Bug 4909) Make sure to load _config-local.bml