Make "currentMemory" @volatile, so that it's reads in ensureFreeSpace() are atomic and up-to-date--i.e., currentMemory can't increase while putLock is held (though it could decrease, which would only help ensureFreeSpace()).

Remove unnecessary entries.get() call.

Miscellaneous fixes for 0.8

- List higher-level projects that run on Spark
- Tweak CSS

Fix spark.io.compression.codec and change default codec to LZF

Allow PySpark to run on Windows

Run script fixes for Windows after package & assembly change

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