BlockManager UI.
code Formatting
Nicer storage level format on RDD page
Merge branch 'master' into blockmanagerUI

Conflicts:
	core/src/main/twirl/spark/deploy/worker/index.scala.html
Merge branch 'master' into blockmanagerUI
Refactor BlockManager UI and adding worker details.
Merge branch 'master' into blockmanagerUI
Add spark.executor.memory to differentiate executor memory from spark-shell memory.
Merge remote-tracking branch 'dennybritz/blockmanagerUI' into blockmanager_ui

Conflicts:
	core/src/main/scala/spark/RDD.scala
	core/src/main/scala/spark/storage/BlockManagerMaster.scala
	core/src/main/scala/spark/storage/StorageLevel.scala
Fix up some problems from the merge
Merge branch 'master' into blockmanager_ui

Conflicts:
	core/src/main/scala/spark/RDD.scala
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'.
code reformatting
switch to TimeStampedHashMap for storing persistent Rdds