Changes stream to implement the Readable interface

[heygambo]

MockFirestoreQuery.prototype.stream was using the underlying EventEmitter to emit the events which bypassed the stream's logic.

This PR changes it to return a Transformable stream.

That will make stream reader functions available like stream.pause(), stream.resume() or stream.read().

The existing tests pass.

[dmurvihill]

Thanks for the contribution, @heygambo. I don't know if you still rely on firebase-mock or not, but we're moving activity over to my fork for now (see #160) and will be reviewing this for an early December release. Cheers.

New PR on the interim repo

[heygambo]

Awesome. Yes, we still use it.
Thanks for taking care of that!

[dmurvihill]

My pleasure. If you've made any changes on your own fork besides this one, a pull request would be welcome. Opening before next Thursday (U.S. Thanksgiving) would give the best chance of getting into the release.

Also, we are looking for maintainers.

[heygambo]

@dmurvihill hey this can be closed here right?

[dmurvihill]

Yes, go ahead and close it. If you want the new change, update your package.json to "firebase-mock": "^2.3.0".