MAPREDUCE-5714. Removed forceful JVM exit in shutDownJob.  
                (Jinghui Wang via Eric Yang)


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1590263 13f79535-47bb-0310-9956-ffa450edef68
Merge branch 'trunk' into HDFS-5168