CI testing seems to be broken?

[skosch]

When I open a new PR, CircleCI says

We couldn't detect the settings for your project! Please make sure you have a configuration file in place, and check our doc about manual build setup in CircleCI 2.0 or CircleCI 1.0.

I'm not sure how to set this up, but it'd be nice to have (especially since we have some pretty good tests now, for a start at least).