media_url definition and workflow

[kvlahromei]

This is an special (complex) case of #7 and #8 At the current doc we say:

A convention for parsing media from this URL has yet to be established, so currently it will be done on a case by case basis much like Twitter.com does. For example, if a jurisdiction accepts photos submitted via Twitpic.com, then clients can parse the page at the Twitpic URL for the image given the conventions of Twitpic.com. This could also be a URL to a media RSS feed where the clients can parse for media in a more structured way.

So we might need to discuss and define:

• supported filetypes/content of the URLs (images, video, ...)
• supported URLs(flickr, facebook, ...)
• supported services and procedures to get content (e.g. Open Graph , oEmbed, crawler, ...)