Font references broken on SSL sites.

Ran into issues using this on an SSL secured site because the font references were hard-coded to http://

Instead of trying to shoehorn in some protocol detection, I chose to use [protocol-relative](http://www.paulirish.com/2010/the-protocol-relative-url/) links.  There are some [arguments against them](https://yoast.com/relative-urls-issues/) but I still think it's a better solution since [it can be tricky to detect ssl status](http://stackoverflow.com/questions/1175096/how-to-find-out-if-you-are-using-https-without-serverhttps).

I also switched the admin calls to https when fetching font data, since it was related and seemed like a good idea.