Use stubs instead of mocks for DAGSchedulerSuite.
Merge branch 'master' into nomocks

Conflicts:
	core/src/test/scala/spark/scheduler/DAGSchedulerSuite.scala
Override DAGScheduler.runLocally so we can remove the Thread.sleep.
Fix MapOutputTrackerSuite.
Merge remote-tracking branch 'stephenh/nomocks'

Conflicts:
	core/src/main/scala/spark/storage/BlockManagerMaster.scala
	core/src/test/scala/spark/scheduler/DAGSchedulerSuite.scala