An extra "-" is added to filenames when dumping datasets

A resource called "title.ext" becomes "name-.ext". Resource title is still the same, but the path differs.

```
      "name": "s-ptarmigan-counts-readme-pdf",
      "path": "data/s-ptarmigan-counts-readme-.pdf",
      "title": "S_ptarmigan_counts_readme.pdf"
```