Replace fitvids.js source with unminified version.
Revert previous commit.

Seems we can get around directly modifying fitvids.js.
Sloppy fix. Very sloppy.
Let's modify fitvids …
Pick up (sloppy again) the idea to ignore elements by class, ref. https://github.com/davatron5000/FitVids.js/pull/90#issuecomment-12709439
Find Tumblr audio embeds and add CSS-class to make fitvids.js ignore them.
For elements appended via infinite scroll, we don't need to prevent fitvids from anything regarding Tumblr audio embeds.
Merge branch 'feature/fitvids.js-for-all-post-types' into develop