Tweak group culture : hat tip abe.pm.org

And Aaron for getting the ball rolling.

https://twitter.com/aaroncrane/status/390606792793030656
Remove outdated link to YAPC::EU 2013

Sadly, there doesn't yet seem to be a website for YAPC::EU 2014, due to be
held in Sofia.
Add link to LPW 2013
Add placeholder for YAPC::EU 2014