[maven-release-plugin] prepare release 0.20.1

git-svn-id: https://svn.apache.org/repos/asf/rave/branches/0.20.1@1453656 13f79535-47bb-0310-9956-ffa450edef68
[maven-release-plugin] prepare for next development iteration

git-svn-id: https://svn.apache.org/repos/asf/rave/branches/0.20.1@1453658 13f79535-47bb-0310-9956-ffa450edef68