Add Microdata to event detail

[markjames]

Theres a question over Multipack classifies as SocialEvent, BusinessEvent or some other Event type.

Possibly it should be: http://schema.org/SocialEvent/Meetup

[tgvashworth]

This'd certainly be a good addition.

[markjames]

I've got some of the event information in (using http://schema.org/SocialEvent/Meetup as the itemtype), although it has messed up some of the styling. Will fix it up and pull request it.