Extra fields and keywords on first page of dataset creation not saved

[wardi]

When customizing a dataset form with IDatasetForm and adding extra fields or keyword fields to the first page (package_basic_fields.html) of the dataset creation the extra fields and keyword fields are not saved.

Extra fields on the last page (package_metadata_fields.html) are saved properly.

Extra fields and keyword fields on both pages are saved properly when editing a dataset (both pages are combined into a single page)