[#2434] Correctly shutdown bossExecutor in OioServerSocketChannelFactory

Motivation:
At the moment the bossExecutor is not shutdown correctly. So the threads may never exit.

Modifications:
Correctly shutdown bossExecutor.

Result:
Threads are correctly stopped.

src/main/java/org/jboss/netty/channel/socket/oio/OioServerSocketChannelFactory.java

@@ -145,11 +145,13 @@ public class OioServerSocketChannelFactory implements ServerSocketChannelFactory
 
     public void shutdown() {
         if (shutdownExecutor) {
+            ExecutorUtil.shutdownNow(bossExecutor);
             ExecutorUtil.shutdownNow(workerExecutor);
         }
     }
 
     public void releaseExternalResources() {
+        ExecutorUtil.shutdownNow(bossExecutor);
         ExecutorUtil.shutdownNow(workerExecutor);
     }
 }