Remove hardcoded http protocol to allow for automatic SSL compatibility.

In order to get our SSL'ed Omeka instance working (mbda.berry.edu) without several of the browsers throwing the user-terrifying 'some items are insecure' kinds of messages, I had to adjust the CDN calls to drop the hardcoded http:.

I would assume others who would want an SSLed site would have to do the same, and thought you might want to change it to something along these lines so it would be automatic. Thanks!