Various code style fixes, mostly from IntelliJ IDEA

core/src/main/scala/spark/Accumulators.scala

core/src/main/scala/spark/BlockStoreShuffleFetcher.scala

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

core/src/main/scala/spark/ClosureCleaner.scala

core/src/main/scala/spark/CoGroupedRDD.scala

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

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

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

core/src/main/scala/spark/HadoopWriter.scala

core/src/main/scala/spark/JavaSerializer.scala

core/src/main/scala/spark/Logging.scala

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

core/src/main/scala/spark/ParallelCollection.scala

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

core/src/main/scala/spark/SampledRDD.scala

core/src/main/scala/spark/ShuffledRDD.scala

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

core/src/main/scala/spark/Split.scala

core/src/main/scala/spark/UnionRDD.scala

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