With the new routes, all pages are not all at the same folder level anymore
(e.g. /shaare and /shaare/123), so we can't just use './' everywhere.
The most consistent way to handle this is to prefix all path with the proper variable,
and handle the actual path in controllers.
Includes:
- og:title
- og:type -> article
- og:image -> if there is a thumbnail
- og:url -> permalink
- og:description -> first 300 chars of raw description
- article:published_time
- article:modified_time
- article:tag -> one OG meta tag for each shaare tag
Fixes#258
