SVG max-age bug

Hi Frederick,

Great to see the new version out today.

This bug on svg still needs a fix. SVG files are using HTML max-age settings but need to use the settings for images. Note it’s not max-age, not expiry. Expiry is fine but not max-age at the moment.

The bug discussion is here: https://github.com/szepeviktor/w3-total-cache-fixed/issues/242