title: SimpleMessageListenerContainer is not recover after stoping it
body: <p>When a certain event arrives, I stop my <code>rabbitmq listner</code> using <code>container.stop();</code> and after the needed job is done, I restart it with <code>container.start()</code>, but when a new event arrives, I get following error:</p>
  
  <pre><code>Exception in thread "SimpleAsyncTaskExecutor-1" 2016-04-22T16:20:53.646  WARN 15336 --- [cTaskExecutor-1] o.s.a.r.l.SimpleMessageListenerContainer : Consumer raised exception, processing can restart if the connection factory supports it
  java.lang.NullPointerException: null
      at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.isActive(SimpleMessageListenerContainer.java:756) ~[spring-rabbit-1.4.3.RELEASE.jar:na]
      at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.access$600(SimpleMessageListenerContainer.java:82) ~[spring-rabbit-1.4.3.RELEASE.jar:na]
      at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer$AsyncMessageProcessingConsumer.run(SimpleMessageListenerContainer.java:1100) ~[spring-rabbit-1.4.3.RELEASE.jar:na]
      at java.lang.Thread.run(Thread.java:745) [na:1.8.0_77]
  </code></pre>