corrections in CHANGES.txt as result of comparing jira and CHANGES records before release of 1.2.0 rc

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-1.2@1479466 13f79535-47bb-0310-9956-ffa450edef68
updated release notes for 1.2.0

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-1.2@1479473 13f79535-47bb-0310-9956-ffa450edef68