title and <meta> for session pages

[tarnas14]

generate nice title and meta tags for specific session pages, so it expands nicely in communicators

• add an icon (frontier reverse would be nice and edgy)
• for session page:
  • title: number of players, number of points (10), list of factions
  • description: include what factions are playing and how many VP they have, sort descending by vp
• include og:title, og:description, og:image -> include the image of the winning faction