Add spark.executor.memory to differentiate executor memory from spark-shell memory.
Call removeJob instead of killing the cluster.
Handle Master telling the Worker to kill an already-dead executor.
Restore SPARK_MEM in executorEnvs.
Fix SPARK_MEM in ExecutorRunner.
Don't bother creating an exception.
Fix Worker logInfo about unknown executor.
Replace old 'master' term with 'driver'.
Change time unit in MetadataCleaner to seconds
SPARK-658: Adding logging of stage duration
Renaming stage finished function
Making submission time a field
add long and float accumulatorparams
Some DEBUG-level log cleanup.

A few changes to make the DEBUG-level logs less
noisy and more readable.

- Moved a few very frequent messages to Trace
- Changed some BlockManger log messages to make them
  more understandable

SPARK-666 #resolve
Merge pull request #423 from squito/long_float_accums

add long and float accumulatorparams
Merge pull request #424 from pwendell/logging-cleanup

Some DEBUG-level log cleanup.
Merge branch 'master' into driver

Conflicts:
	core/src/main/scala/spark/SparkContext.scala
	core/src/main/scala/spark/SparkEnv.scala
	core/src/main/scala/spark/deploy/LocalSparkCluster.scala
	core/src/main/scala/spark/executor/StandaloneExecutorBackend.scala
	core/src/main/scala/spark/scheduler/cluster/SparkDeploySchedulerBackend.scala
	core/src/main/scala/spark/scheduler/cluster/StandaloneClusterMessage.scala
	core/src/main/scala/spark/scheduler/cluster/StandaloneSchedulerBackend.scala
	core/src/main/scala/spark/storage/BlockManagerMaster.scala
	core/src/main/scala/spark/storage/ThreadingTest.scala
	core/src/test/scala/spark/MapOutputTrackerSuite.scala
Units from ms -> s
Add RDD.toDebugString.

Original idea by Nathan Kronenfeld.
Merge pull request #413 from pwendell/stage-logging

SPARK-658: Adding logging of stage duration