Not sure if it would help in your situation but I've moved all of my github pages to netlify.com and they have a one button https feature for custom domains.
I did the same. Between Netlify and Zeit.co's Now, I don't see any reason to complain about HTTPS, not to mention the devOps issues that both these services solve.
SSL requires one click with Netlify, and it's on by default with Now.
