HADOOP-7713. Update CHANGES.txt
HADOOP-7713. Update CHANGES.txt

zjshen/hadoop-YARN-2928-POC,zjshen/hadoop-YARN-2928-POC,zjshen/hadoop-YARN-2928-POC,zjshen/hadoop-YARN-2928-POC,zjshen/hadoop-YARN-2928-POC,zjshen/hadoop-YARN-2928-POC,zjshen/hadoop-YARN-2928-POC