Preparing for hadoop-2.1.1-beta release.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1523892 13f79535-47bb-0310-9956-ffa450edef68
Added ASL2 header to releasenotes.html.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1523904 13f79535-47bb-0310-9956-ffa450edef68