D7 custom date format

gistfile1.txt

/**
* Note that the new format won't be visible unless you go save the date formats page or call drupal_static_reset('date_format_type_format')
*/

/**
 * Implements hook_date_formats().
 */
function mymodule_date_formats() {
  $formats = array();
  $formats[] = array(
    'type' => 'mymodule_date_long',
    'format' => 'd-M-Y H:i',
    'locales' => array(),
  );
  return $formats;
}

/**
 * Implements hook_date_format_types().
 */
function mymodule_date_format_types() {
  $types = array();
  $types['mymodule_date_long'] = t('My Long Date Format');
  return $types;
}