Image minification

A separate image minification workflow is included to help automate this process but without the slowing down development/deployment workflows (the level of optimisation can result in a slow process that you wouldn't want to run repeatedly).

Be aware that the workflow will overwrite the existing contents of the "images" folder, so ensure you have all changes committed first. It may also be worthwhile committing the original, unminified versions of images to source control so they can be retrieved if ever needed again.