language independent fields aren't displayed correctly on the translation add form

[agitator]

working on it at https://github.com/plone/plone.app.multilingual/tree/agitator-LI-fixes

[agitator]

fixed and merged into https://github.com/plone/plone.app.multilingual/tree/datakurre-lif
requires plone.z3cform >= 0.8.1 to work