Simplified forms.

The first approach was too django-incompatible. Passing kwargs from a formset
of formsets is nearly impossible to implement without going too deep into the
django internals.
Made admin for DatedValueType be translatable.
Added language settings
Added app settgins defaults.
Added modified login check decorator, that allows custom check functions.

otherwise it's exactly the login_required decorator from django auth.
Added manangement view and a basic template