WP-2952: Ensure that duplicated author data isn't saved.
WP-2989 Added new field field_profile_visibility
WP-2989 Changed widget for field_profile_visibility to select
WP-2989 Added gsb_feature_base_fields_field_attach_form to setup states
WP-2989 Cleaned up a little of the code in gsb_feature_base_fields_field_attach_form()
WP-2952: Remove reference when Other is selected.
WP-3069 Added allowed values function for profile visibility.