Bug: GitHub usernames are case-insensitve, but team-sync isn't

[joshua-cannon-techlabs]

I just heard from a colleague that they keep getting emailed about being removed from a Team they are still a part of.

I suspect it is because they're name in GitHub is defined as Foo-Bar, but our yml file has them as foo-bar.

[rmacklin]

Thanks for filing this issue. It makes sense that this would happen since the code doesn't do anything special to handle usernames in a case-insensitive manner. I can fix that.