Add https option for includes

[Jeremy Hopkins]

When a site is running in https the links to google fonts etc cause a warning to be shown particularly in IE.

We need to detect whether https is being used ($CFG->wwwroot can tell us this) and alter the prefix of included fonts (Google / FA) accordingly.

It seems both Google and FA will load over https so should not present a problem.

[Jeremy Hopkins]

Another update has set both google fonts and font awesome to call over https so this is now resolved.

There is a small performance overhead associated with doing this but I do not believe there should be an issue leaving it like this.

It will remove complexity in the code if we just leave as https.