Thumbnails of images have inconsistent dimensions in 'New file' tab

[oanalavinia]

Steps to reproduce:

1. Create a folder and go to New file tab
2. Upload a file of different format (like pdf)
3. Upload large images with different dimensions

The result is that the thumbnails of these images could occupy a big portion of the screen, compared to the dimension of a pdf file for example.
Also, if a folder containing multiple of these type of images will be uploaded, it could be hard to scroll though them.

[mflorea]

Looks like a use case not covered by #6. @ignatescustefan please take a look.

[ignatescustefan]

Here is a screenshot from the application after the fix: