fix: don't call bluebird.defer

[james-owen]

Bluebird's defer method is deprecated. Switching to the strategy here http://bluebirdjs.com/docs/api/deferred-migration.html

[laddhoffman-swarm]

This does not seem to work. From MDN

The arguments object is a local variable available within all non-arrow functions.

Here you're using an arrow function, and I get ReferenceError: arguments is not defined.

[laddhoffman-swarm]

Here's a suggested fix,

...
const promise = new Promise((_resolve, _reject) => {
  resolve = _resolve;
  reject = _reject;
  });
...