Sort static files with modification time in reverse order

[rpeyron]

Hello, a very small PR to have the most recent uploaded files in first positions. It is so useful when you have numerous static files. This is certainly not the best way to do it, I hope you can get the issue and implement it the right way.

It would also be nice to be able to upload static files directly from the pick file modal, but I have not been able to include the StaticFiles view (with directory view) in the modal.