Call a single meetup function per exercism/exercism.io#950

- Per https://github.com/exercism/xclojure/issues/21 we don't want to be doing metaprogramming at this point (Or in the example code's case, dynamically creating functions)
Modify example to fit new tests

- Fixes #21
Merge pull request #35 from mathias/change_meetup_problem

Change meetup problem