Use Eventbrite API to populate workshop information

NOTE: The event description relies on the explanation of the workshop content be
wrapped in an element with an id of "#what-will-i-learn" so that we're not
pulling the entirety of the event description, which is really an FAQ.

@conchan - Can you take a look at the styilng of the event description? There is a UL that could use some love.

With no upcoming event:
![railsbridge boston - ruby and rails workshop 2014-08-12 00-38-53 2014-08-12 01-38-17](https://cloud.githubusercontent.com/assets/602470/3886724/dd52f52c-21e2-11e4-95df-64015f48063d.jpg)

With upcoming event:
![railsbridge boston - ruby and rails workshop 2014-08-12 01-39-05 2014-08-12 01-39-13](https://cloud.githubusercontent.com/assets/602470/3886728/ff7f79ae-21e2-11e4-98a5-bda727922745.jpg)

I’ve tried that in the past, but Middleman doesn’t seem to recognize that those extensions exist for some reason.