Feature Request: Auto Thumbnails generation

[oesah]

Currently, we need to define the sizes of an image in the settings and then upload images that adhere to these dimensions. This means, we need to generate and upload several different files. Instead, wouldn't it be better to upload one image only and then auto generate all the sizes from the settings? Then I only need to take care of the aspect ratio of the image (1:1, 1:2, etc.) and the rest is automated.

What do you think? I can contribute if you like, I would like to heavily use this plugin for several clients of mine with multiple Django Websites.