[maven-release-plugin] prepare release 0.21.1

git-svn-id: https://svn.apache.org/repos/asf/rave/branches/0.21.1@1478530 13f79535-47bb-0310-9956-ffa450edef68
[maven-release-plugin] prepare for next development iteration

git-svn-id: https://svn.apache.org/repos/asf/rave/branches/0.21.1@1478532 13f79535-47bb-0310-9956-ffa450edef68