We need tests

[syvb]

We should run tests on every PR, before Chaosbot can merge them.

[mdcfe]

To facilitate testing, we should separate out lookAtPrs into multiple separate functions that perform single tasks, possibly into separate files as well.

I'd personally suggest Jest as a framework as it's easy to pick up, and we could use Travis to run the tests before allowing the PR to be merged.

In addition, we could clean up the code by moving to using async functions and awaiting promises instead of using .then, for example changing this:

function lookAtPrs() {
    repo.listPullRequests({
        state: "open",
        base: "master" //ignore non-master PRs
    }).then(function (prs) {
        prs = prs.data;
        // ...
    }
}
lookAtPrs()

to this:

async function lookAtPrs() {
    let prs = await repo.listPullRequests({
        state: "open",
        base: "master" //ignore non-master PRs
    });
    prs = prs.data;
    // ...
}
await lookAtPrs();