use HTTPS urls

[obfusk]

No description provided.

[obfusk]

@AndreMiras @tshirtman

Most of those URLs -- e.g. in the README -- aren't very important.

But downloading e.g. ant and kivy over unencrypted http w/o checking e.g. a SHA256 checksum is pretty bad security practice nowadays.

[tshirtman]

Didn't test the updated instructions, but indeed it's important to switch to https as much as possible.

[obfusk]

I tested the HTTPS URLs to see if they work, though I did not check whether the result is identical.

This is why I added a www. prefix to the sphinx URLS, since the URL without the prefix doesn't work over HTTPS.

[AndreMiras]

LGTM

[obfusk]

Given the security implications and otherwise harmlessness of these changes may I suggest doing a point release that includes (only) these changes?