Merge pull request #828 from mateiz/sched-improvements

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

core/src/main/scala/spark/MapOutputTracker.scala

core/src/main/scala/spark/RDD.scala

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

core/src/main/scala/spark/Utils.scala

core/src/main/scala/spark/deploy/DeployMessage.scala

core/src/main/scala/spark/deploy/worker/ExecutorRunner.scala

core/src/main/scala/spark/deploy/worker/Worker.scala

core/src/main/scala/spark/executor/Executor.scala

core/src/main/scala/spark/rdd/BlockRDD.scala

core/src/main/scala/spark/rdd/CartesianRDD.scala

core/src/main/scala/spark/rdd/ZippedPartitionsRDD.scala

core/src/main/scala/spark/rdd/ZippedRDD.scala

core/src/main/scala/spark/scheduler/DAGScheduler.scala

core/src/main/scala/spark/scheduler/DAGSchedulerEvent.scala

core/src/main/scala/spark/scheduler/ResultTask.scala

core/src/main/scala/spark/scheduler/ShuffleMapTask.scala

core/src/main/scala/spark/scheduler/Task.scala

core/src/main/scala/spark/scheduler/TaskLocation.scala

core/src/main/scala/spark/scheduler/TaskResult.scala