Import translations po file on install.

gistfile1.php

/**
 * Imports translations from a .po file into the local database.
 *
 * @param string $filepath
 *   Full filepath to a .po translations file.
 */
function maya_updates_api_import_translations($filepath, $langcode) {
  _maya_updates_api_load_locale();
  drupal_load('module', 'file');
  watchdog(__FUNCTION__, 'Importing @file string translations.', array('@file' => $filepath), WATCHDOG_NOTICE);
  // No need to use drupal_basename() in this case, and it requires loading up file.inc.
  $file = file_save_data(file_get_contents($filepath), 'public://' . basename($filepath), FILE_EXISTS_RENAME);
  _locale_import_po($file, $langcode, LOCALE_IMPORT_OVERWRITE, 'default');
}

/**
 * Loads locale module files which are required to import new languages and
 * translations.
 *
 * @see maya_updates_api_enable_default_language()
 * @see maya_updates_api_import_translations()
 */
function _maya_updates_api_load_locale() {
  drupal_load('module', 'locale');
  module_load_include('inc', 'locale');
  module_load_include('inc', 'locale', 'locale.admin');
  require_once DRUPAL_ROOT . '/includes/locale.inc';
}