[SPARK-4973][CORE] Local directory in the driver of client-mode continues...

[SPARK-4973][CORE] Local directory in the driver of client-mode continues remaining even if application finished when external shuffle is enabled

When we enables external shuffle service, local directories in the driver of client-mode continue remaining even if application has finished.
I think local directories for drivers should be deleted.

Author: Kousuke Saruta <sarutak@oss.nttdata.co.jp>

Closes #3811 from sarutak/SPARK-4973 and squashes the following commits:

ad944ab [Kousuke Saruta] Fixed DiskBlockManager to cleanup local directory if it's the driver
43770da [Kousuke Saruta] Merge branch 'master' of git://git.apache.org/spark into SPARK-4973
88feecd [Kousuke Saruta] Merge branch 'master' of git://git.apache.org/spark into SPARK-4973
d99718e [Kousuke Saruta] Fixed SparkSubmit.scala and DiskBlockManager.scala in order to delete local directories of the driver of local-mode when external shuffle service is enabled

core/src/main/scala/org/apache/spark/storage/DiskBlockManager.scala

@@ -166,7 +166,7 @@ private[spark] class DiskBlockManager(blockManager: BlockManager, conf: SparkCon
   /** Cleanup local dirs and stop shuffle sender. */
   private[spark] def stop() {
     // Only perform cleanup if an external service is not serving our shuffle files.
-    if (!blockManager.externalShuffleServiceEnabled) {
+    if (!blockManager.externalShuffleServiceEnabled || blockManager.blockManagerId.isDriver) {
       localDirs.foreach { localDir =>
         if (localDir.isDirectory() && localDir.exists()) {
           try {