Disable streamed output on build() until it is fixed in Docker

Talked with @vieux earlier and he agrees that Docker's output for `/build` isn't the way it should be. `/build` should return a HTTP chunk-encoded stream like all the other streamed endpoints of the Docker API.

Until then, ignore the `stream` parameter of `docker-py`'s `build()` method so we return something a bit more useful. Once Docker has a usable output for `/build`, we'll be able to uncomment this code.