Prevent other sites from loading the login page in an iframe.
Prevent other sites from loading the login page in an iframe.

This patch adds the X-Frame-Options header to prevent simpleSAMLphp
pages from being used in iframes on third-party sited.

Thanks to Thijs Kinkhorst for adding this!
tectronics/simplesamlphp,vivekrajenderan/simplesamlphp,tectronics/simplesamlphp,tectronics/simplesamlphp,tectronics/simplesamlphp,tectronics/simplesamlphp,vivekrajenderan/simplesamlphp,vivekrajenderan/simplesamlphp,vivekrajenderan/simplesamlphp,vivekrajenderan/simplesamlphp