JCRVLT-41 ImportMode=UPDATE deletes existing nodes

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/commons/filevault/trunk@1575052 13f79535-47bb-0310-9956-ffa450edef68
@trivial use latest released version

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/commons/filevault/trunk@1575053 13f79535-47bb-0310-9956-ffa450edef68