PySpark: implementing subtractByKey(), subtract() and keyBy()
Don't send SIGINT to Py4J gateway subprocess.

This addresses SPARK-885, a usability issue where PySpark's
Java gateway process would be killed if the user hit ctrl-c.

Note that SIGINT still won't cancel the running s

This fix is based on http://stackoverflow.com/questions/5045771
RDD sample() and takeSample() prototypes for PySpark
Change docs color theme for 0.8
New hardware provisioning doc, and updates to menus
Make HadoopRDD's configuration accessible
Also add getConf to NewHadoopRDD
Merge pull request #876 from mbautin/master_hadoop_rdd_conf

Make HadoopRDD's configuration accessible
More doc improvements + better warnings when you haven't built Spark
Update docs about HDFS versions
Merge pull request #869 from AndreSchumacher/subtract

PySpark: implementing subtractByKey(), subtract() and keyBy()
Merge pull request #870 from JoshRosen/spark-885

Don't send SIGINT / ctrl-c to Py4J gateway subprocess
Merge pull request #861 from AndreSchumacher/pyspark_sampling_function

Pyspark sampling function
More updates, describing changes to recommended use of environment vars
and new Python stuff
Fixes suggested by Patrick
Another fix suggested by Patrick
Merge pull request #877 from mateiz/docs

Doc improvements for 0.8
Added stageId <--> jobId mapping
DAGScheduler:
  - style fixes
  - clearOldValues for new TimeStampedHashMaps
  - log unexpected cleanup of data structures
  - cleanup stageToInfos and stageIdToLogIds
cleanup