BUG: Number of documents in investigation incorrect

[jlstro]

Describe the bug If one uploads an excel file to Aleph that has more than one sheets, each of these sheets will be counted like it was a separate file. I understand why this is happening with the csv converts, but it feels very unintuitive and makes users question whether or not there should be more for them to see. I did not test it but I assume the behaviour is the same for zip files, pst files and other files Aleph expands.

To Reproduce Steps to reproduce the behavior:

1. Create an investigation
2. Upload a xls file with more than one sheet

Expected behavior Show each file as one file or specify that "Document" means something else here.

Screenshots