I figured there is not way I can grade (pass / fail) an assignment on GitHub Education. This is something that I really miss. Anyway, I wrote a small Node project to help me out with that (also using travis-ci).
Maybe this is something useful for you guys: https://github.com/maciossek/hft-assignments-check-web
I also explained my motivation a little on medium: https://medium.com/@maciossek/github-classroom-workflow-as-a-teacher-4cba250cee39