Revert "YARN-2603. ApplicationConstants missing HADOOP_MAPRED_HOME (Ray Chiang via aw)"

This reverts commit b0a9cd37ab9ef45ed9a71b04f1634fa54dd4c438.

Conflicts:
	hadoop-yarn-project/CHANGES.txt
YARN-2766. Made ApplicationHistoryManager return a sorted list of apps, attempts and containers. Contributed by Robert Kanter.
HDFS-7395. BlockIdManager#clear() bails out when resetting the GenerationStampV1Limit. Contributed by Haohui Mai.
YARN-2856. Fixed RMAppImpl to handle ATTEMPT_KILLED event at ACCEPTED state on app recovery. Contributed by Rohith Sharmaks