Metadata element repeatability should be able to respect locales

When metadata elements are repeatable, repeatability is allowed without regard to locale. That is, if three locales are available for cataloguing (say en_US, de_DE and fr_FR) up to three values may be added, but all could be in English (or French or German).

The system should offer the option to work as preferred labels do where you can only add one value per-locale. Once a value for that locale is added that locale will be gray and not clickable.