Feeds: Update AS schema to v2

[silverbucket]

The Feeds platform needs some reworking in how the AS objects look. Using collections type

{
  context: "feeds",
  type: "fetch",
  actor: {
     id: 'aUniqueUserString',
     type: "person",
  },
  target: {
     id: 'https://blog.example.com/rss',
     type: "page"
  },
  object: {
     type: "parameters",
     limit: 10,    // default 10
     property: 'date',
     after: 'Tue Nov 26 2013 02:11:59 GMT+0100 (CET)',
 }

Without any parameters specified, the platform will return most recent 10 articles fetched from the feed.

Example of the resulting JSON AS Object:

  {
    context: 'feeds',
    type: 'collection',
    actor: {
      type: 'page',
      name: 'Best Feed Inc.',
       id: 'https://blog.example.com/rss',
       description: 'Where the best feed comes to be the best',
       image: {
         type: 'image',
         width: '144',
         height: '144',
        url: 'https://example.com/images/bestfeed.jpg',
         mediaType: "image/jpeg"
      },
      favicon: 'https://example.com/favicon.ico',
      categories: ['best', 'feed', 'aminals'],
      language: 'en',
      author: 'John Doe'
    },
    totalItems: 10,
    items: [{
      id: "https://example.com/articles/about-stuff",
      type: 'document',
      title: 'About stuff...',
      url: "https://example.com/articles/about-stuff",
      date: "2013-05-28T12:00:00.000Z",
      datenum: 1369742400000,
      brief_html: "Brief synopsis of stuff...",
      brief_text: "Brief synopsis of stuff...",
      html: "Once upon a time...",
      text: "Once upon a time...",
      media: [{
        type: 'audio',
        length: '13908973',
        mediaType: 'audio/mpeg',
        url: 'https://example.com/media/thing.mpg'
      }],
      tags: ['foo', 'bar']
    }, {
      id: "https://example.com/articles/blog-post",
      type: 'document',
      title: 'Blog post...',
      url: "https://example.com/articles/blog-post",
      date: "2013-05-29T14:00:00.000Z",
      datenum: 1369742400000,
      brief_html: "Brief synopsis of stuff...",
      brief_text: "Brief synopsis of stuff...",
      html: "Another blog post...",
      text: "Another blog post...",
      media: [{
        length: '13908973',
        type: 'audio/mpeg',
        url: 'https://example.com/media/thing.mpg'
      }],
      tags: ['foo']
    }, { ... }]
  }

#594