db_to_form_package_schema() strips tracking summary, isopen

[seanh]

If an IDatasetForm plugin with a db_to_form_schema() based on db_to_form_package_schema() (which is in turn based on default_package_schema()) is in use then the 'tracking_summary' dict and the 'isopen' bool get stripped from package dicts during validation, e.g. during package_show(), and these values are then not available to templates.