fix install SQL

This extension won't install. It seems like perhaps at some point mte_install.sql was passed through Smarty? But no longer.

I made a change to support the default domain on install, not the current domain. That's out of expediency. Those SQL lines that require a domain ID can either a) be moved into PHP and executed with CRM_Core_DAO::executeQuery(), or better yet, a modern setting.php file.