YARN-1258: Move to 2.2.1 in CHANGES.txt

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YARN-1288. Make Fair Scheduler ACLs more user friendly (Sandy Ryza)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1534316 13f79535-47bb-0310-9956-ffa450edef68