When the FileImporter successfully finishes an import it should not only add a `NullRevision` to inform about the import step in the revision history but should also add an entry to the upload log and one to the import log. These should all be associated with the importing user and be timestamped with the import date.
Having the `NullRevision` and the upload log entry is the default for uploads   (although it leads to "doubled" entries on the history page). Since we, apart from the upload, do an import, having an import log entry is the right thing to do.
 Add an entry to the import log associated with the null revision of the import
 Add an entry to the upload log associated with the null revision of the import (this is still slightly unclear, if we need that entry, too)
Most probably we will still just have one entry (the null revision) in the page history.
This includes tests