/**
 * Implements hook_field_info_alter().
 */
function {{ machine_name }}_field_info_alter(&$info) {
  // Add a setting to all field types.
  foreach ($info as $field_type => $field_type_info) {
    $info[$field_type]['settings'] += array(
      'mymodule_additional_setting' => 'default value',
    );
  }

  // Change the default widget for fields of type 'foo'.
  if (isset($info['foo'])) {
    $info['foo']['default widget'] = 'mymodule_widget';
  }
}