Don't force iterating chunked (streamed) responses

Was tearing my hair out trying to work out why Rails was buffering my entire (ostensibly) streamed response.  Finally realized that rack-livereload was screwing me over.  Don't do that, rack-livereload.

And while we're at it, don't mess with inlined content either, since the chunked header might not get there before rack-livereload in the stack.