Image metadata and retina display support

Hello! I would like to contribute with a few changes to Aqua Resizer, but I'm new to Github and I'm not really sure if I made the commit the right way. If you didn't get it, here is the fork I made: https://github.com/S3bY/Aqua-Resizer
My addition is image metadata, so all images created by the script be deleted from the server when the original is removed.
I also added the retina display support suggested by wpexplorer in this thread: https://github.com/syamilmj/Aqua-Resizer/issues/36