Ported performance and FT improvements from latest streaming work

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

core/src/main/scala/spark/DaemonThreadFactory.scala

core/src/main/scala/spark/HadoopRDD.scala

core/src/main/scala/spark/KryoSerializer.scala

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

core/src/main/scala/spark/NewHadoopRDD.scala

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

.../src/main/scala/spark/network/ConnectionManagerTest.scala

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

...main/scala/spark/scheduler/cluster/ClusterScheduler.scala

...c/main/scala/spark/scheduler/cluster/TaskSetManager.scala

...a/spark/scheduler/mesos/CoarseMesosSchedulerBackend.scala

core/src/main/scala/spark/storage/BlockManager.scala

core/src/main/scala/spark/storage/BlockManagerWorker.scala

core/src/main/scala/spark/storage/BlockMessage.scala

core/src/main/scala/spark/storage/BlockStore.scala

core/src/main/scala/spark/storage/StorageLevel.scala

core/src/main/scala/spark/util/AkkaUtils.scala