SLING-3656 - nested nodes below file/jcr:content cause problems on
import and export

Added SerializationManager methods to help converting between repository
and OS paths.

git-svn-id: https://svn.apache.org/repos/asf/sling/trunk@1604266 13f79535-47bb-0310-9956-ffa450edef68
SLING-3656 - nested nodes below file/jcr:content cause problems on
import and export

Handle child nodes of nt:resource nodes under nt:file nodes in the
ImportRepositoryContentAction

git-svn-id: https://svn.apache.org/repos/asf/sling/trunk@1604267 13f79535-47bb-0310-9956-ffa450edef68
SLING-3656 - nested nodes below file/jcr:content cause problems on
import and export

Added a more convoluted import test case under ContentImportTest to
validate nested nodes under file/jcr:content get properly imported.

git-svn-id: https://svn.apache.org/repos/asf/sling/trunk@1604268 13f79535-47bb-0310-9956-ffa450edef68