Ensure EOS sent before close() called.

[GoogleCodeExporter]

Work out whether EOS bucket sent down bucket chain before close() called.

If it is, user could set Connection close response header and EOS might close 
socket, allowing long action in close() not to hold open active connection.

Original issue reported on code.google.com by Graham.Dumpleton@gmail.com on 17 Oct 2012 at 12:08