[maven-release-plugin] prepare release openjpa-parent-2.3.0

git-svn-id: https://svn.apache.org/repos/asf/openjpa/branches/2.3.x@1540825 13f79535-47bb-0310-9956-ffa450edef68
[maven-release-plugin] prepare for next development iteration

git-svn-id: https://svn.apache.org/repos/asf/openjpa/branches/2.3.x@1540827 13f79535-47bb-0310-9956-ffa450edef68