Update config with new optional parameters

[simonberger]

Just a follow up to my config issue. I needed to configure multiple x509 certs and fe,lt lucky finding out it is possible in onelgins package. Maybe its new I don't know. Their example has the following part:

 /* In some scenarios the IdP uses different certificates for
 * signing/encryption, or is under key rollover phase and
 * more than one certificate is published on IdP metadata.
 * In order to handle that the toolkit offers that parameter.
 * (when used, 'x509cert' and 'certFingerprint' values are
 * ignored).
 */
// 'x509certMulti' => array(
//      'signing' => array(
//          0 => '<cert1-string>',
//      ),
//      'encryption' => array(
//          0 => '<cert2-string>',
//      )
// )

I didn't look if there are more new values.