More doc updates, and moved Serializer to a subpackage.

...la/spark/bagel/examples/WikipediaPageRankStandalone.scala

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

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

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

core/src/main/scala/spark/Partitioner.scala

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

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

core/src/main/scala/spark/api/java/JavaDoubleRDD.scala

core/src/main/scala/spark/api/java/JavaPairRDD.scala

core/src/main/scala/spark/api/java/JavaRDD.scala

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

core/src/main/scala/spark/serializer/Serializer.scala

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