Temporary fix #89 Case create show-stopper. Provisional diagnoses widget constant error

Although the value for the record field 'Title' is always set after
the desired Provisional diagnosis being selected from the combo,
the POST always returns 'Provisional diagnosis is required, please
correct'. Seems that the 'required_subfields' option is only evaluated
by recordswidget.js when the 'More' button is clicked.
Maybe due to incompatibility issues amongst required specific subfields
and Plone's required Archetype fields.