Pass along card/attempt data in problemDone

Summary:
This makes it so listeners on the "problemDone" event can get more info
if they so please. This is useful for auxilliary UI that may not live
directly inside of the exercise UI.

Test Plan:
- ran a local python server for "localMode", got questions wrong on an
  addition exercise, then got it right, made sure nothing blew up
- ran a local KA dev server, opened that same exercise. In chrome console, typed:
  $(Exercises).on("problemDone", function(e, data) { console.log(data); });
  did some questions, watch output

Reviewers: alpert, eater

Reviewed By: alpert

Differential Revision: http://phabricator.khanacademy.org/D2150