remove to much uuids from list

Just to avoid problems when creating documents from nodes.

Solved issue: #545
i think this could be done more efficient. inside the `!empty($uuids)` check if count($nodes) < count($uuids) and if so, do a foreach on the $uuids and unset every item in that list from $ids (no need to check, unsetting something that does not exist does not cost more than the check).

i checked, getNodesByIdentifier is indeed supposed to not return nodes that do not exist, rather than doing an error.