Another round of Netty fixes.
1. Avoid race condition between stop and copier completion
2. Handle socket exceptions by reporting them and filling in a failed
FetchResult
Make connect timeout configurable
Delete a file for a block if it already exists.
Reuse the file object as it is valid after delete
var to val
Don't write zero block files with java serializer
Pass in bufferSize to BufferedOutputStream
Clean up variables and counters in BlockFetcherIterator
modify to pass job annotation by localProperties and use daeamon thread to do joblogger's work
Merge branch 'master' of https://github.com/mesos/spark
delete test code for joblogger in SparkContext
not check return value of eventQueue.take
Merge branch 'master' of git://github.com/mesos/spark into netty-dbg
Merge branch 'netty-dbg' of github.com:shivaram/spark into netty-dbg
modify sparklister function interface according to comments
Fix some comments and style
edit according to comments
some format modification
small format modification
small modify in DAGScheduler