FEATURE: Optimzer shouldn't make files bigger

[rolandschuetz]

When I have a already for the use case highly optimized image (e.g. JPEG quality of 30%) the image optimizer creates a worse file size.

The image optimizer should always compare file size and choose the smaller version.

[aertmann]

Good idea, feel free to open a PR that solves that.

[rolandschuetz]

I'm not using the package anymore.