swcarpentry/bc — pull request #923 by BillMills (2014-12-18 02:48:09+00:00)
Title: made challenge make sense

the challenge in the middle of this lesson referred to data that didn't exist (there is no `dates` in `Site`). There's a nearly identical challenge at the bottom of the lesson that fixes this a different way - do we want both or just one? Whichever exact wording we choose should be in the middle of the lesson, rather than the end, to remind instructors to break up the lecture as much as possible.