Merge branch 'master' into Pool_UI

Conflicts:
	core/src/main/scala/spark/SparkContext.scala
	core/src/main/scala/spark/scheduler/DAGScheduler.scala
	core/src/main/scala/spark/scheduler/SparkListener.scala
	core/src/main/scala/spark/scheduler/cluster/ClusterTaskSetManager.scala
	core/src/main/scala/spark/scheduler/cluster/TaskSetManager.scala
	core/src/main/scala/spark/scheduler/local/LocalTaskSetManager.scala
	core/src/main/scala/spark/ui/jobs/IndexPage.scala
	core/src/main/scala/spark/ui/jobs/JobProgressUI.scala