FileSet filename(s) are not being exported

[bkiahstroud]

Mirror ticket in Bulkrax: samvera/bulkrax#425

Testing Instructions

1. Login as an admin
2. Navigate to Dashboard > Importers > New
3. Fill out required fields and upload a CSV containing at least one FileSet with metadata (title, description, etc)
4. Click "Create and Import"
5. Navigate to the importer's show page. After a couple minutes, refresh the page and ensure the entries succeeded
6. Navigate to Dashboard > Exporters > New
7. Select "Export From" > "Importer". Select the importer under "Importer". Fill out required fields. Click "Create and Export"
8. After a couple minutes, refresh the page and click the download icon next to the exporter
9. Open the downloaded CSV. Verify that all FileSet(s) with titles had their titles exported

[rschwab]

This has been resolved, confirmed in http://digitalcollections-staging-sandbox.library.ucsc.edu/exporters/7?locale=en