SLING-4098 - Full coverage aggregates nested under a partial coverage
aggregate incorrectly deleted when a sibling resource is published

Unify repository path extraction logic in VltSerializationManager -
getRepositoryPath now hosts the more extensive logic which originally
resided in readSerializationData .

git-svn-id: https://svn.apache.org/repos/asf/sling/trunk@1634147 13f79535-47bb-0310-9956-ffa450edef68