The project page is on transifex. There all the localizations are maintained. If you want to contribute, check if there are untranslated or wrong translated words.
Or you can start translating a new language if you speak it ;-)
If you like to contribute to the project just let me know which ideas you have!
Copyright (C) 2015 Paul Woitaschek
The license is GnuGPLv3. With contributing you agree to license your code under the same conditions.