Change translations files from javascript to JSON data

[Nico-Duduf]

• Update translator.jsxinc (in particular getAvailableLanguages and maybe other functions) Update translator.jsxinc to use JSON #35
• Create specs for the JSON object (details : JSON translation file specs #23)
• Implement JSON in DuTranslator instead of parsing jsxinc JSON translation data files parser #36
• Convert current translations to JSON (write a small tool to automate this using the current parser in Dutranslator)
• Reimplement QTranslator::load() and QTranslator::translate() to use our own JSON translation files #22 reimplement QTranslator