[maven-release-plugin] prepare release xbean-3.15

git-svn-id: https://svn.apache.org/repos/asf/geronimo/xbean/trunk@1539516 13f79535-47bb-0310-9956-ffa450edef68
[maven-release-plugin] prepare for next development iteration

git-svn-id: https://svn.apache.org/repos/asf/geronimo/xbean/trunk@1539518 13f79535-47bb-0310-9956-ffa450edef68