kazoo_ui with dutch strings

- User Portal translated in dutch (NL) 80%
- Config (config/lang/nl.js) translated in dutch (NL) 80%
- Core (login page etc) translated in dutch (NL) 100%

All english en.js files are copied to nl.js files, most of them need to
be translated, but for the working/testing the files need to be in the
ui, to prevent load errors.