L358 render_gallery_index receives a param file_dep and does not use it

nitpick: In the same method, around L378 when appending to photo array, it looks better if more uniform, by example

```python
            thumb_url = url_from_path(thumb)
            photo_array.append({
                'url': url_from_path(img),
                'url_thumb': thumb_url,
```
changes to
```python
            photo_array.append({
                'url': url_from_path(img),
                'url_thumb': url_for_path(thumb),
```