Allow any name in VPNAction

This is a fix for issue #263.

It allows VPNAction to have any name as parameter (for details see the issue).

It also keeps backwards-compatibility with the old format so existing actions won't break.

I have updated the English and German strings files, but don't speak the other languages, so that is a todo.

(Also, you should really change your strings files to UTF-8, else git won't diff them properly)