Revert "[SPARK-5342] [YARN] Allow long running Spark apps to run on secure YARN/HDFS"

.../apache/spark/deploy/ExecutorDelegationTokenUpdater.scala

.../main/scala/org/apache/spark/deploy/SparkHadoopUtil.scala

.../src/main/scala/org/apache/spark/deploy/SparkSubmit.scala

.../scala/org/apache/spark/deploy/SparkSubmitArguments.scala

.../apache/spark/executor/CoarseGrainedExecutorBackend.scala

...ark/scheduler/cluster/CoarseGrainedSchedulerBackend.scala

docs/security.md

...va/org/apache/spark/launcher/SparkSubmitOptionParser.java

...g/apache/spark/deploy/yarn/AMDelegationTokenRenewer.scala

...cala/org/apache/spark/deploy/yarn/ApplicationMaster.scala

.../src/main/scala/org/apache/spark/deploy/yarn/Client.scala

.../scala/org/apache/spark/deploy/yarn/ClientArguments.scala

...la/org/apache/spark/deploy/yarn/YarnSparkHadoopUtil.scala

...test/scala/org/apache/spark/deploy/yarn/ClientSuite.scala

...scala/org/apache/spark/deploy/yarn/YarnClusterSuite.scala

...g/apache/spark/deploy/yarn/YarnSparkHadoopUtilSuite.scala