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.
Units from ms -> s
Merge pull request #413 from pwendell/stage-logging

SPARK-658: Adding logging of stage duration
Merge branch 'master' of github.com:mesos/spark
Fix code that depended on metadata cleaner interval being in minutes
Simplify checkpointing code and RDD class a little:

- RDD's getDependencies and getSplits methods are now guaranteed to be
  called only once, so subclasses can safely do computation in there
  without worrying about caching the results.

- The management of a "splits_" variable that is cleared out when we
  checkpoint an RDD is now done in the RDD class.

- A few of the RDD subclasses are simpler.

- CheckpointRDD's compute() method no longer assumes that it is given a
  CheckpointRDDSplit -- it can work just as well on a split from the
  original RDD, because it only looks at its index. This is important
  because things like UnionRDD and ZippedRDD remember the parent's
  splits as part of their own and wouldn't work on checkpointed parents.

- RDD.iterator can now reuse cached data if an RDD is computed before it
  is checkpointed. It seems like it wouldn't do this before (it always
  called iterator() on the CheckpointRDD, which read from HDFS).
Merge branch 'master' into blockmanager_info