Updating branch-2's MAPREDUCE CHANGES.txt to reflect the recent rebase of unreleased 2.3 to more latest branch-2.
Updating trunk's MAPREDUCE CHANGES.txt to fix more differences with branch-2's CHANGES.txt
MAPREDUCE's CHANGES.txt is foobar'ed. There are still a bunch of misplaced CHANGES.txt entries - not fixing them now.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1562945 13f79535-47bb-0310-9956-ffa450edef68