Run oxipng on pngs inbound to the CDN (e.g. icons, gallery images, etc)

[triphora]

https://github.com/shssoichiro/oxipng
Worth taking into consideration how inbound images are named (with the sha1 hash of the image), so remember to hash the file and create the name after running it through oxipng (again, only if it's a png file)

Do not require it, make it a user-configurable option as they're uploading the file