OAK-1656 - Provide lazy iterator for FileDataStore.getAllIdentifiers

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1583602 13f79535-47bb-0310-9956-ffa450edef68
OAK-1655 - DataStoreBlobStore does not take into maxLastModifiedTime when fetching all chunks

If the maxLastModifiedTime <= 0then all files would be returned

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1583603 13f79535-47bb-0310-9956-ffa450edef68