Preview displays broken images if files are not images

[kmiyashiro]

Currently preview does not support non-image files and displays a broken image. Ideally it would display the file name and size, or some other reasonable default.

[jelhan]

We could also display a preview if it's a text file using canvas. There seem to be many use cases where users should upload text files (logs, csv etc.). Could fall back to file name and size if it's a binary file but not an image.