Do not create symlink for local add file. Instead, copy the file.

This prevents Spark from changing the original file's permission, and
also allow add file to work on non-posix operating systems.
Fixed the flaky unpersist test in RDDSuite.
More block manager cleanup.

Implemented a removeRdd method in BlockManager, and use that to
implement RDD.unpersist. Previously, unpersist needs to send B akka
messages, where B = number of blocks. Now unpersist only needs to send W
akka messages, where W = the number of workers.
Incorporated Charles' feedback to put rdd metadata removal in
BlockManagerMasterActor.
Merge pull request #636 from rxin/unpersist

Unpersist More block manager cleanup.
Fixed memory leak in DAGScheduler- needs more tests under error conditions.
Removed copyright
CSD version numbering and distribution management
Bump some dependencies, pin others, for Scala 2.9.2
DAGSchedulerSuite now part of core/src/test/scala/spark/scheduler
wip: Bringing Jon's DAGScheduler tests into the new DAGSchedulerSuite
[maven-release-plugin] prepare release spark-parent-0.8.0-candidate-csd-1
[maven-release-plugin] prepare for next development iteration
Specified commons-io version for spark-core
[maven-release-plugin] prepare release spark-parent-0.8.0-candidate-csd-2
[maven-release-plugin] prepare for next development iteration
[maven-release-plugin] prepare release spark-parent-0.8.0-candidate-csd-3
[maven-release-plugin] prepare for next development iteration
[maven-release-plugin] prepare release spark-parent-0.8.0-candidate-csd-4
[maven-release-plugin] prepare for next development iteration