Change Spark version to 0.7.0-SNAPSHOT
Updates based on Spark shuffle refractoring.
Move Shark's CoGroupedRDD from spark.rdd to spark package, to avoid conflict.
Merge remote-tracking branch 'src/master' into master-updates
Set default cache storage level to MEMORY_AND_DISK
Adding TaskContext to compute methods in Shark RDDs (patch by Thomas Dudziak)
Merge pull request #75 from harveyfeng/master-updates

Updates based on Spark shuffle refractoring for 0.7 upgrade.
Merge pull request #84 from mbautin/taskcontext-fix

Adding TaskContext to compute methods in Shark RDDs (patch by Thomas Dudziak)
Updated Kryo registrator for Kryo 2.x.