Revert "destroy instead of end http connection at end of pipeline"

This reverts commit 4ce1e1fca5.

To fix test-http-full-response.js. Clearly this is not the correct solution.
Probably need idle timeouts.

lib/http.js

@@ -606,7 +606,7 @@ function connectionListener (socket) {
     res.shouldKeepAlive = shouldKeepAlive;
     res.addListener('flush', function () {
       if (flushMessageQueue(socket, responses)) {
-        socket.destroy();
+        socket.end();
       }
     });
     responses.push(res);