Use website url for Vimeo videos

Vimeo video pages have a swf for the `og:video` meta tag, which cannot be parsed by VideoInfo into something meaningful. So a Vimeo video is missing is `id`, `duration` and embed code.

Switching to `og:url` specifically for Vimeo pages fixes this (the video metadata returned is now far more detailed).

This doesn't feel like an ideal solution to the problem, but it works. If you have a better solution then I'm happy to see that implemented instead.