have -dev languages to be prod languages + dbg (bug 1016125)

r? @clouserw

This was causing Punjabi (pa) to not be included in the `body[data-languages]` set in the `index.html` template used by Fireplace.

I've just made all the other settings files include all of prod's languages + 'dbg'. If there are some languages we want to test on -dev/stage before we ship them to production, then we can add those to the appropriate settings files when the time comes.