Don't prematurely close responses we don't transform
Don't prematurely close responses we don't transform

This currently breaks static resources served by Pyramid, or any response which is intended to be served piecemeal. I'm not entirely sure that the app_iter should be closed at all here.
huubbouma/diazo,huubbouma/diazo,ebrehault/diazo,huubbouma/diazo,ebrehault/diazo,ebrehault/diazo