Feature/pmctl

/to @kraman @rmg, can one of you review, pls.

This is a dependency of https://github.com/strongloop/strong-pm/pull/14
This callback gets a second argument that is an array of the results. Not sure if it would be an improvement or just a code shuffle, but with some small modifications this _could_ be:
```js
function (err, results) {
  assert.ifError(err);
  assert.deepEqual(results, [0, 1, 2]);
  console.log('PASS');
  process.exit(0);
}
```