Load CNDied Webjars dependencies over HTTPS

I figured out that the default configuration is not working when used in HTTPS context.

By default the dependencies are linked to an HTTP resource (eg: https://cdn.jsdelivr.net/webjars/xx/yy/zz.min.js), and the browers forbid to fetch an insecure file in HTTPS.

This PR just ensure that dependencies are always loaded in https (works in http & https).
If for any reason you don't want that, I recommend to explicitly describe this tricks in the documentation.
Shouldn't this use the protocol-matching url `//cdn.jsdelivr.net/webjars` ?