[maven-release-plugin] prepare for next development iteration

git-svn-id: https://svn.apache.org/repos/asf/sling/trunk@1576226 13f79535-47bb-0310-9956-ffa450edef68
Use latest snapshots

git-svn-id: https://svn.apache.org/repos/asf/sling/trunk@1576228 13f79535-47bb-0310-9956-ffa450edef68