Fix mixed content issue on demo page

[hg8]

The demo page is currently not working because of Mixed Content errors.

Mixed Content: The page at 'https://t00rk.github.io/bootstrap-material-datetimepicker/' was loaded over HTTPS, but requested an insecure stylesheet 'http://fonts.googleapis.com/css?family=Roboto:400,500'. This request has been blocked; the content must be served over HTTPS.

Mixed Content: The page at 'https://t00rk.github.io/bootstrap-material-datetimepicker/' was loaded over HTTPS, but requested an insecure script 'http://momentjs.com/downloads/moment-with-locales.min.js'. This request has been blocked; the content must be served over HTTPS.

This fix the issue by loading remaining libraries with https.