Dropzone is awesome, so I added an "auto" option for thumbnailWidth and thumbnailHeight

This makes it possible to customize the resizing routine for uses cases like a Facebook-style image upload, where the thumbnail(s) fill up a given container that is constrained by its width or its height

In other words, it makes it possible to scale thumbnails (not crop) 

There was no test case for the resize function, so I added one for the default settings. (100, 100)

Thanks