client needs to be able to stream responses

[joedevivo]

Right now all the responses are pretty much based on waiting for the whole response and an end_stream flag. #55 introduces the ability to set a callback module send partial bodies, but on the client side we have no way of consuming data that way. Ideally we should be able to, even if for no other reason than to adequately test #55

[tony612]

Any progress for this issue?

[tsloughter]

I'm finally working on this.

Thinking about just doing the interface the same as the server, with callbacks.

[tsloughter]

Should be fixed in #127