Check whether langpacks are installed before using them
Translations for native packages are obtained by shelling out to gettext(1) with TEXTDOMAINDIR set to /usr/share/locale-langpack which fails if no language packs are installed and/or available. Add a fallback to /usr/share/locale for the "translationPath" property and TEXTDOMAINDIR environment variable.
Hardcoding paths isn't good but it's already there and I think we should fix that systematically another day.
This fixes #3 (closed).
After applying this we should probably revert the workarounds.