public static function set_activation()
 {
     flush_rewrite_rules();
     if (!current_user_can('activate_plugins')) {
         return;
     }
     $plugin = isset($_REQUEST['plugin']) ? $_REQUEST['plugin'] : EM_ESS::NAME;
     check_admin_referer("activate-plugin_{$plugin}");
     if (!EM_MS_GLOBAL || EM_MS_GLOBAL && is_main_blog()) {
         ESS_Database::createTable();
     }
     ESS_IO::set_crons();
 }