version to 0.4.0
version to 0.4.0

* Allow no shutdown timeout with `WorkerPoolSpy` (#12)
* Add `start` method to `DatWorkerPool`, delay spawning workers (#13)
* Add callbacks for workers and the queue (#15)
* Update `WorkerPoolSpy`, spy init args and call queue callbacks (#16)

/cc @kellyredding

redding/dat-worker-pool