Future proof media for Comment json_metadata

[kellyjanderson]

The current specification has a dedicated field for images and video. This does not allow room for other forms of media, or future forms of media. I would recommend using a media[] field with entries that are [{ "url": "http://url.to.media" , "type": "image"}, { "url": "http://url.to.media" , "type": "video"}, { "url": "http://url.to.media" , "type": "audio"}, etc...]

{
    "app": "steemit/1.23",
    "format": "html",
    "tags": ["steemit", "steem"],
    "users": ["ned", "dan"],
    "media": [{ "url": "http://url.to.media" , "type": "image"}, { "url": "http://url.to.media" , "type": 
                    "video"}, { "url": "http://url.to.media" , "type": "audio"}, etc...],
    "status": "archived",
    "canonical": "http://blog.steem.io/steem/@ned/the-first-phase-of-the-steem-faq-and-wikee-consolidation-of-knowledge"
}