Rename spark package to org.apache.spark

* RDD, *RDDFunctions -> org.apache.spark.rdd
* Utils, ClosureCleaner, SizeEstimator -> org.apache.spark.util
* JavaSerializer, KryoSerializer -> org.apache.spark.serializer

ports and creates noisy log messages

Don't require the spark home environment variable to be set for standalone mode (change needed by SIMR)

Extend QuickStart to include next steps

Various UI tweaks

Doc improvements for 0.8

- Use "fluid" layout that can expand to wide browser windows, instead of
  the old one's limit of 1200 px
- Remove unnecessary <hr> elements
- Switch back to Bootstrap's default theme and tweak progress bar colors
- Make headers more consistent between deploy and app UIs
- Replace some inline CSS with stylesheets

spark-daemon

and new Python stuff

Pyspark sampling function

Don't send SIGINT / ctrl-c to Py4J gateway subprocess

PySpark: implementing subtractByKey(), subtract() and keyBy()

Make HadoopRDD's configuration accessible

Fix broken build by removing addIntercept

Adding linear regression and refactoring Ridge regression to use SGD