Can't set max_workers when using async

[jameskhedley]

Hi, I'd love to bump the number of workers I use when iterating documents using async requests.

However I can't see a way of passing this in. Am I missing something, or would you like a patch that lets you pass it via kwargs? Happy to provide.

See line 47 of resource.py. It could be made:

self._session = FuturesSession(kwargs.get('max_workers',2))

Cheers,
James