prepare release

git-svn-id: https://svn.apache.org/repos/asf/maven/shared/trunk@1582507 13f79535-47bb-0310-9956-ffa450edef68
[maven-release-plugin] prepare release maven-shared-components-20

git-svn-id: https://svn.apache.org/repos/asf/maven/shared/trunk@1582508 13f79535-47bb-0310-9956-ffa450edef68