[maven-release-plugin] prepare release org.apache.sling.jcr.resource-2.2.8

git-svn-id: https://svn.apache.org/repos/asf/sling/trunk@1478689 13f79535-47bb-0310-9956-ffa450edef68
[maven-release-plugin] prepare for next development iteration

git-svn-id: https://svn.apache.org/repos/asf/sling/trunk@1478691 13f79535-47bb-0310-9956-ffa450edef68