Fix hash bug - caused failure after 35k stages, sigh
Address review comments - rename toHash to nonNegativeHash
updated content
SPARK-660: Add StorageLevel support in Python

It uses reflection... I am not proud of that fact, but it at least ensures
compatibility (sans refactoring of the StorageLevel stuff).
Memoize StorageLevels read from JVM
Remove reflection, hard-code StorageLevels

The sc.StorageLevel -> StorageLevel pathway is a bit janky, but otherwise
the shell would have to call a private method of SparkContext. Having
StorageLevel available in sc also doesn't seem like the end of the world.
There may be a better solution, though.

As for creating the StorageLevel object itself, this seems to be the best
way in Python 2 for creating singleton, enum-like objects:
http://stackoverflow.com/questions/36932/how-can-i-represent-an-enum-in-python
Export StorageLevel and refactor
Work in progress:

- Add job scheduling docs
- Rename some fair scheduler properties
- Organize intro page better
- Link to Apache wiki for "contributing to Spark"
More fair scheduler docs and property names.

Also changed uses of "job" terminology to "application" when they
referred to an entire Spark program, to avoid confusion.
Added cluster overview doc, made logo higher-resolution, and added more
details on monitoring
Whoopsy daisy
Some tweaks to CDH/HDP doc
Ganglia sink
Merge pull request #898 from ilikerps/660

SPARK-660: Add StorageLevel support in Python
Review comments
Add better docs for coalesce.

Include the useful tip that if shuffle=true, coalesce can actually
increase the number of partitions.

This makes coalesce more like a generic `RDD.repartition` operation.

(Ideally this `RDD.repartition` could automatically choose either a coalesce or
a shuffle if numPartitions was either less than or greater than, respectively,
the current number of partitions.)
Adding more docs and some code cleanup
Updated cluster diagram to show caches
Fix target JVM version in scala build
Merge pull request #908 from pwendell/master

Fix target JVM version in scala build