Add Ability to Use Custom Image Sizes

Hi there,

Awesome plugin, thank you so much for all your hard work on this!

It’d be even better if you could add the ability to customize all the image sizes so that I can use any pre-defined or theme defined image size. I’ve modified your code myself and placed the image sizes I want, but it’d be even better to have fields to specify the images sizes to use for the main image(s) and the thumbnails. It doesn’t look like it’d be too hard and I’d be happy to modify the code and provide you the updated file(s). Let me know ??

Thanks!