Fixes for example section in qunit/sinonjs section

I noticed that one of the example sections ("collections") in the qunit/sinonjs chapter was using the jasmine functions (describe, expect, it) instead of the qunit style so I migrated the code with as few changes as possible.

I loaded it into the qunit-koans section to verify, which is where I found that the latest git version of qunit doesn't have `expect` as a global anymore, so I pinned the version of qunit to match the css version used there so that the koan tests would pass initially (or more specifically so that the test suite would actually run).

So this updated section doesn't pass (I believe because it is an excerpt and not complete), but it does actually run to the end of the suite, so it's better than it was before.

Feel free to cherry-pick if you don't want all of the changes.  I tried to aim for consistency with the rest of the examples but they aren't all necessary or maybe they're not quite your style.

Thanks for the great book, I've really enjoyed it.