GitHub Pages may soon support SSL!
Looks like GitHub are testing SSL support of GitHub Pages.
I was checking out some settings on my GitHub account today and I noticed in the Security section, several messages like this:
Hmm… repo.pages_https_redirect_disabled …I don’t remember changing that setting. I don’t even know where that
setting is! I reached out to the awesome GitHub support team and they tell me that they’ve been working on an
“experimental” feature: 
Sorry for the audit log noise! An experimental feature was accidentally enabled for your repository…
So, it looks like we may be seeing SSL on GitHub Pages sometime soon!