Preparing for hadoop-2.1.1-beta release.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2.1-beta@1523893 13f79535-47bb-0310-9956-ffa450edef68
Setting version in branch-2.1-beta to 2.1.2-SNAPSHOT.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2.1-beta@1523895 13f79535-47bb-0310-9956-ffa450edef68
Added ASL2 header to releasenotes.html.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2.1-beta@1523905 13f79535-47bb-0310-9956-ffa450edef68