Use keepalive on 401.

If client requests keepalive and server allows it, reuse the socket

Author: taer

src/main/java/com/ning/http/client/providers/netty/NettyAsyncHttpProvider.java

@@ -2103,6 +2103,9 @@ public Object call() throws Exception {
                             }
                         };
 
+                        if (future.getKeepAlive()) {
+                            future.setReuseChannel(true);
+                        }
                         if (future.getKeepAlive() && response.isChunked()) {
                             // We must make sure there is no bytes left before executing the next request.
                             ctx.setAttachment(ac);