Move extra credit below all other tasks in both versions

This is not a bug fix but rather a (tentative of) user experience improvement. When doing the koans, I was expecting to do AboutExtraCredit last. But as of now AboutRegex is after AboutExtraCredit in the lessons order:

~~~
Thinking TelevisionTest
  [...]

Thinking AboutRegex
 [...]

Thinking AboutExtraCredit
  test_extra_credit_task has expanded your awareness.

[...]

If you want more, take a look at about_extra_credit_task.py
~~~

Wouldn't it be better to have AboutExtraCredit as the very last task? If so, this PR just changes the lesson's order.