Remove orphan field instances in ScaldAtomController::removeType()

ScaldAtomController::addType() creates field instances for scald_thumbnail, scald_authors, scald_tags fields for the bundle being created.
ScaldAtomController::removeType() doesn't remove them when the bundle is deleted, so field instances reference nonexistent bundle. This leads to PHP notices when visiting admin/reports/fields page (field list report).

I suggest to remove field instances in ScaldAtomController::removeType():

  foreach (array('scald_thumbnail', 'scald_authors', 'scald_tags') as $field_name) {
    $instance = field_info_instance('scald_atom', $field_name, $type);
    if (!empty($instance)) {
      field_delete_instance($instance, FALSE);
    }
  }