Exception when calling AMRMClientAsync::close() (or stop())

[Tyson Condie]

Branch: 2.1.0-beta

When I call close or stop on my AMRMClientAsync instance, I get the following 
exception:

java.lang.InterruptedException: sleep interrupted
        at java.lang.Thread.sleep(Native Method)
        at 
org.apache.hadoop.yarn.client.api.async.impl.AMRMClientAsyncImpl$HeartbeatThread.run(AMRMClientAsyncImpl.java:255)
13/08/11 08:05:41 INFO impl.AMRMClientAsyncImpl: Interrupted while waiting for 
queue
java.lang.InterruptedException
        at 
java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.reportInterruptAfterWait(AbstractQueuedSynchronizer.java:2017)
        at 
java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2052)
        at 
java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:442)
        at 
org.apache.hadoop.yarn.client.api.async.impl.AMRMClientAsyncImpl$CallbackHandlerThread.run(AMRMClientAsyncImpl.java:281)