Main thing is the addition of a Queue between reading from the backend
server's httplib.Response and the frontend client's webob.Response,
allowing timeouts on either end to tear down the sockets.
Also, Connection: close headers were added to backend requests since
we only ever do one request per connection; this will tear down those
connections more quickly after the request is complete.
Finally, the eventlet.wsgi.WRITE_TIMEOUT is set in case the Eventlet
version supports it, timing out writes to client connections if they
take too long to read.
Change-Id: I18c7559442cf17a47ff30690ffc75010a7f003c4
f643a58d32