Shuffle Performance fix: Use netty embeded OIO file server instead of ConnectionManager
Shuffle Performance Optimization: do not send 0-byte block requests to reduce network messages
change reference from io.Source to scala.io.Source to avoid looking into io.netty package

Signed-off-by: shane-huang <shengsheng.huang@intel.com>
fix a bug in netty Block Fetcher

Signed-off-by: shane-huang <shengsheng.huang@intel.com>
Merge branch 'shuffle-performance-fix-0.7' of github.com:shane-huang/spark into shufflemerge

Conflicts:
	core/src/main/scala/spark/storage/BlockManager.scala
	core/src/main/scala/spark/storage/DiskStore.scala
	project/SparkBuild.scala
Moved BlockFetcherIterator to its own file.
Cleaned up BlockManager and BlockFetcherIterator from Shane's PR.
Cleaned up the Java files from Shane's PR.
Cleaned up Scala files in network/netty from Shane's PR.
Minor style fix in DiskStore...
Cleaned up connection manager (moved many classes to their own files).
Added test for Netty suite.
Merge branch 'master' of github.com:mesos/spark into shufflemerge

Conflicts:
	core/src/main/scala/spark/storage/BlockManager.scala
	core/src/test/scala/spark/DistributedSuite.scala
	project/SparkBuild.scala
Merge pull request #602 from rxin/shufflemerge

Manual merge & cleanup of Shane's Shuffle Performance Optimization