Handle StatusNoContent responses appropriately.

When the router received a 204 from an application, it would add a
'Transfer Encoding: chunked' header to the response.  This would cause
some upstream http clients to hang in a read waiting for more data about
the response.

Signed-off-by: Maria Shaldibina <mariash@pivotallabs.com>
Auto-merge remote-tracking branch 'upstream/master'