structured properties should be exposed as python dicts

[chason]

Structured OGP properties (i.e. image) should be represented with a similar structure in the class. For example:

<meta property="og:image" content="http://example.com/ogp.jpg" />
<meta property="og:image:secure_url" content="https://secure.example.com/ogp.jpg" />
<meta property="og:image:type" content="image/jpeg" />
<meta property="og:image:width" content="400" />
<meta property="og:image:height" content="300" />
<meta property="og:image:alt" content="A shiny red apple with a bite taken out" />

Should probably look something like:

{
  "url": "http://example.com/ogp.jpg",
  "secure_url": "https://secure.example.com/ogp.jpg",
  "type": "image/jpeg",
  "width": 400,
  "height": 300,
  "alt": "A shiny red apple with a bite taken out"
}

Note that the image property is converted into url. This is because og:image and 'og:image:url` are synonyms in OGP.

The structure above and how it is presented in the OGP class are suggestions. If you have a more creative solution with significant benefits, feel free to try it out.