Change design of meetup problem

[kytrinyx]

@pminten brought up a very good point about the API of meetup being
pretty terrible (See exercism/exercism#950).

If the meetup problem has not already been fixed in this track, we should
improve the test suite and example code to give the API a better design.

[mathias]

I have the tests converted to the new API in mathias@e9c0cfc but still need to redo the example. (Hooray for vim macros when I went to rewrite the tests. Saved me a ton of time!)

[kytrinyx]

Sweet, I look forward to seeing it.

[mathias]

Question for the others watching exercism/xclojure: At this point in the exercises, how do we want the simplified meetup example to work? The Java example uses a switch statement, which I could replicate with a cond, but dispatching based on the "schedule" argument could also be done with an inner function using Protocols or Multimethods. I'm just not sure if protocols have been introduced at this point in the exercises for Clojure.

Thoughts? Suggestions?