Make sure conf.py is fully functional after importing a multi-lingual Wordpress site

When importing a Wordpress XML export and extracting posts translations (eg with the --qtranslate option), the resulting "site" is not functional (anymore?) as "nikola build" complains about untitled slugs (it seems to consider the translated posts as independent posts or something like that).

Adding, in conf.py's TRANSLATIONS, an explicit path for each "additional" language found on the original site fixes this problem.

I could check that starting from scratch with python2 and python3 it is possible to go from a xml export to a build+serve (but I did that only on one exported xml file).