Fix client to await the driver pod

[kimoonkim]

@foxish @mccheah

It seems there is a small bug in the current client code. My client exits right away without waiting for the driver pod to complete.

2017-06-02 14:48:36 INFO Client:54 - Waiting for application spark-hdfstest-1496440110123 to finish...
2017-06-02 14:48:36 INFO LoggingPodStatusWatcherImpl:54 - Container final statuses:
Container name: spark-kubernetes-driver
Container image: docker:5000/spark-driver:kimoon-0602-1
Container state: Waiting
Pending reason: PodInitializing
2017-06-02 14:48:36 INFO Client:54 - Application spark-hdfstest-1496440110123 finished.

Think it should have been podCompletedFuture.await below instead of countDown:

override def awaitCompletion(): Unit = {
    podCompletedFuture.countDown()
    logInfo(pod.map { p =>
      s”Container final statuses:\n\n${containersDescription(p)}”
    }.getOrElse(“No containers were found in the driver pod.“))
  }

The client waits for the driver to finish after this patch.

2017-06-02 15:27:41 INFO  LoggingPodStatusWatcherImpl:54 - Container final statuses:


	 Container name: spark-kubernetes-driver
	 Container image: docker:5000/spark-driver:kimoon-0602-1
	 Container state: Terminated
	 Exit code: 0
2017-06-02 15:27:41 INFO  Client:54 - Application spark-hdfstest-1496442152207 finished.
2017-06-02 15:27:41 INFO  ShutdownHookManager:54 - Shutdown hook called
2017-06-02 15:27:41 INFO  ShutdownHookManager:54 - Deleting directory /private/var/folders/6t/m6rqw14s78gbm3ggzsxg_ypr0000gp/T/uploaded-jars-2d319a09-877c-4264-92ec-dd85a24e97ac
2017-06-02 15:27:41 INFO  ShutdownHookManager:54 - Deleting directory /private/var/folders/6t/m6rqw14s78gbm3ggzsxg_ypr0000gp/T/uploaded-files-9a5b0e9f-1b83-483a-9e46-52017fa3f574

[mccheah]

+1 - merge when it's green.

[ash211]

Yep looks right to me. Great catch @kimoonkim !