Replace Vimeo embeds with links

[twm]

Replace a Vimeo embed like this:

<iframe src="https://player.vimeo.com/video/244096946"
    height="500"
    allowfullscreen="allowfullscreen"
    webkitallowfullscreen="webkitallowfullscreen"
    mozallowfullscreen="mozallowfullscreen"
    class="image full"
    frameborder="0"></iframe>

With a thumbnail and link, like YouTube embeds (as implemented in #10).

[twm]

/feed/138/unread/37167/ is another example.