Fix DNS situation

[earwig]

Currently cs241.cs.illinois.edu has an A record for 151.101.44.133, which is an internal IP used by GitHub's CDN. (It isn't even the correct one—if you try host illinois-cs241.github.io you will see different IPs.) This could break at any time, including two hours before an MP is due. GitHub's documentation is pretty clear that it should be a CNAME to illinois-cs241.github.io, but for various reasons UIUC probably won't let us do this. We may have to fall back to self-hosting the HTML on web.engr.illinois.edu. Fortunately, the existing deploy code used for Travis might be easily repurposed to do this.