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
Minor cleanup.
Don't download files to master's working directory.

This should avoid exceptions caused by existing
files with different contents.

I also removed some unused code.
Add synchronization to Executor.updateDependencies() (SPARK-662)
Further simplify getOrElse call.
Make AccumulatorParam an abstract base class.
Refactor daemon thread pool creation.
Use generation numbers for fetch failure tracking
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.