Upate DNOA to support Front-End-Https header as well as X-Forwarded-Proto

Our load balancer system uses Front-End-Https as the header to determine whether a request was terminated with HTTPS.  This header as per http://en.wikipedia.org/wiki/List_of_HTTP_header_fields#Common_non-standard_request_headers is at least partially a standard for some microsoft products (we're actually using a combination of squid and Akamai for our SSL termination).

We've got a work around in place in our client code, but I figured I'd let you decide if you want to include an alternate header in the HTTPS detection.

Thanks