Set protocol relative (let the browser decide)

[rightvision]

In PageRegular.php the protocol for jquery, mootools and google fonts should be
$protocol = '//';
instead of
$protocol = \Environment::get('ssl') ? 'https://' : 'http://';
This will allow Proxy-System with SSL (eg STUNNEL) to run the pages without any error, as with STUNNEL the protocol at the server is still http.

[leofeyer]

Protocol relative URLs are not supported by IE8, therefore we will only implement the feature once we are dropping IE8 support.

[leofeyer]

Meanwhile implemented.