Allow loading header.php outside secure zone
Allow loading header.php outside secure zone

Make header.php a bit more flexible. If a Shib key exists in the
environment, do some shib-related stuff. But if not, just skip
it. It's just logging, so it's not needed if we're outside the secure
zone.

tcmitchell/geni-portal,tcmitchell/geni-portal,tcmitchell/geni-portal,tcmitchell/geni-portal,tcmitchell/geni-portal