set SPARK_USER as ugi's current user
using worker's spark.local.dir value to initialize DiskBlockManager instead of value comes from driver because drivers and worker's mounted disks are heterogeneous
SPARK-1104: kill Process in workerThread of ExecutorRunner
precheck executors's fullId existence in case of throw NoSuchElementException,because it will result in restarting worker actor
Issue with failed worker registrations,Master send RegisterFailed message to let worker process exit
Merge pull request #3 from lalaguozhe/cosmos-spark-0.9.0

Cosmos spark 0.9.0