i18n : add new translations and update existing one

All those translations were performed by professional translators for the next version of Jalios JCMS, in which MediaElement.js will be integrated (to be released in october).

Some translation choice differs from the existing one (specifically for german and chinese), I voluntarily did a different commit to quickly differentiate the new from the updated languages.

I do not speak those languages but trust our translation service provider to do the right choices, that said, it is still possible that some translations contain mistakes or could be improved.