HADOOP-9401. CodecPool: Add counters for number of (de)compressors leased out. (kkambatl via tucu)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1464219 13f79535-47bb-0310-9956-ffa450edef68
MAPREDUCE-5086. MR app master deletes staging dir when sent a reboot command from the RM. Contributed by Jian He


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1464255 13f79535-47bb-0310-9956-ffa450edef68