Merge remote-tracking branch 'origin/master' into python-api

.gitignore

bagel/pom.xml

bin/start-all.sh

bin/start-master.sh

bin/start-slave.sh

bin/start-slaves.sh

core/pom.xml

...op1/scala/org/apache/hadoop/mapred/HadoopMapRedUtil.scala

...ala/org/apache/hadoop/mapreduce/HadoopMapReduceUtil.scala

...op2/scala/org/apache/hadoop/mapred/HadoopMapRedUtil.scala

...ala/org/apache/hadoop/mapreduce/HadoopMapReduceUtil.scala

core/src/main/scala/spark/Aggregator.scala

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

core/src/main/scala/spark/CacheTracker.scala

core/src/main/scala/spark/Dependency.scala

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

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

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

core/src/main/scala/spark/PairRDDFunctions.scala

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