fix NPE on request timeout

abort sets channel to null without closing it, which causes NPE on
getPipeline, which results in FutureTask ressetting without channel
ever being closed.

Author: jloomis

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

@@ -1746,8 +1746,8 @@ public synchronized void run() {
                 if (p != null && p.getRequestTimeoutInMs() != -1) {
                     requestTimeout = p.getRequestTimeoutInMs();
                 }
-                abort(this.nettyResponseFuture, new TimeoutException(String.format("No response received after %s", requestTimeout)));
                 markChannelNotReadable(channel.getPipeline().getContext(NettyAsyncHttpProvider.class));
+                abort(this.nettyResponseFuture, new TimeoutException(String.format("No response received after %s", requestTimeout)));
 
                 this.nettyResponseFuture = null;
                 this.channel = null;