Change sample code in example 2

- AsyncHttpClient is an interface. Instantiate with concrete implementation instead.

Author: anuragkapur

README.md

@@ -48,7 +48,7 @@ You can also accomplish asynchronous (non-blocking) operation without using a Fu
 import org.asynchttpclient.*;
 import java.util.concurrent.Future;
 
-AsyncHttpClient asyncHttpClient = new AsyncHttpClient();
+AsyncHttpClient asyncHttpClient = new DefaultAsyncHttpClient();
 asyncHttpClient.prepareGet("http://www.example.com/").execute(new AsyncCompletionHandler<Response>(){
 
     @Override