Review comment changes and update to org.apache packaging

core/src/main/scala/org/apache/spark/SparkContext.scala

core/src/main/scala/org/apache/spark/SparkEnv.scala

...spark/scheduler/cluster/SparkDeploySchedulerBackend.scala

core/src/main/scala/org/apache/spark/ui/SparkUI.scala

core/src/main/scala/org/apache/spark/ui/UIUtils.scala

core/src/main/scala/org/apache/spark/util/Utils.scala

docs/running-on-yarn.md

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

...apache/spark/deploy/yarn/ApplicationMasterArguments.scala

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

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

...n/scala/org/apache/spark/deploy/yarn/WorkerRunnable.scala

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

...apache/spark/scheduler/cluster/YarnClusterScheduler.scala