Add CI to verify exercises against example implementation

[ErikSchierboom]

@loziniak The PR currently fails. This is due to the test runner's output not being conform the specification.
Here is some sample output of the test runner:

{"version":2,"status":"ignored","message":null,"tests":[{"name":"Convert an array to linked list, and then from linked list back to array","status":"pass","message":"✓","output":"","test_code":"solution = [3 6 1]"},{"name":"Convert from array, reverse the list, and covert to array","status":"ignored","message":"✓","output":null,"test_code":"solution = none"}]}

The problem is that the general and test status fields are set to ignored, which is not one of the three allowed values (pass/fail/error): https://exercism.org/docs/building/tooling/test-runners/interface
I assume this is because, well, the tests are ignored. The solution is for the test runner to un-ignore the tests before it runs them. Let me know if you have any questions.

Closes #48

[loziniak]

That's because of line:

test-init/limit %simple-linked-list.red 1

Which executes only first test, rest is ignored. What is the preferred behavior, should test-runner run all the tests by default?

[ErikSchierboom]

What is the preferred behavior, should test-runner run all the tests by default?

Yes, that is correct!