#26: Fix response chunking for Apache. Again, still cannot verify the chunked transfer header is being sent (blaming PHP black magic here), but we have hard evidence from curl that shows MgSlimChunkWriter (using Slim's output APIs) causes 90-95% wait time and 5-10% transfer time, while with the MgHttpChunkWriter (using the suggested flush/ob_flush technique) there is minimal wait time with most of the time spent on transfer, which is what we're after.