Merge remote-tracking branch 'apache/master' into filestream-fix

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

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

core/src/main/scala/org/apache/spark/SparkConf.scala

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

...in/scala/org/apache/spark/api/java/JavaSparkContext.scala

core/src/main/scala/org/apache/spark/api/java/package.scala

...src/main/scala/org/apache/spark/broadcast/Broadcast.scala

core/src/main/scala/org/apache/spark/broadcast/package.scala

...n/scala/org/apache/spark/deploy/worker/CommandUtils.scala

.../scala/org/apache/spark/deploy/worker/DriverWrapper.scala

.../scala/org/apache/spark/deploy/worker/WorkerWatcher.scala

...rc/main/scala/org/apache/spark/storage/BlockManager.scala

core/src/test/scala/org/apache/spark/SparkConfSuite.scala

...ala/org/apache/spark/deploy/worker/DriverRunnerTest.scala

...a/org/apache/spark/deploy/worker/WorkerWatcherSuite.scala

...he/spark/util/collection/ExternalAppendOnlyMapSuite.scala

docs/configuration.md

docs/graphx-programming-guide.md

examples/pom.xml

...g/apache/spark/streaming/examples/StreamingExamples.scala