Update JS libraries and load them over HTTPs

[cdman]

This makes the page work when loaded over HTTPs (otherwise it gives mixed mode warning / refuses to load the assets on some browsers).

[cdman]

Hello,

Thank you for merging the change. I see that in the end you chose the protocol independent URLs instead of always using HTTPS (ie. src="// instead of src="https://).

While this may be faster in some edge-cases, I personally prefer to just use https:// always since:

• protocol relative (//) does not work when the main page was loaded locally (ie. through the file:// protocol) because then it tries to complete it with file:// leasing to links like file://d3js.org/d3.v3.min.js which won't work
• the overhead of HTTPS on a well-tuned CDN like the one from Google is very small, and the user most probably has the given files already in the cache (from other sites which also use the Google CDN)