Implement version 3 spec of the test runner

[junedev]

Resolves #32

[coveralls]

Pull Request Test Coverage Report for Build 4186189182

• 57 of 75 (76.0%) changed or added relevant lines in 3 files are covered.
• 19 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-3.8%) to 74.021%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
testrunner/ast.go	13	16	81.25%
testrunner/execute.go	39	54	72.22%
<!--	Total:	57	75	76.0%	-->

Files with Coverage Reduction	New Missed Lines	%
testrunner/execute.go	19	72.08%
<!--	Total:	19		-->

Totals
Change from base Build 3660797032:	-3.8%
Covered Lines:	416
Relevant Lines:	562

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💛 - Coveralls

[junedev]

@ErikSchierboom Is there any other place then the JSON the test runner outputs where I need to specifiy that it is version 3 now?

[ErikSchierboom]

@junedev Nope, we've only dabbled with other locations for the version with representers.

[junedev]

@ErikSchierboom I updated the code as discussed so either all or none of the tests have task ids. Do you want to take another look? (FYI The setup is such that when the task id is 0 in the code, the field will not show up in the resulting JSON.)

[junedev]

It's slightly hard to review due to not seeing the generated results.json, but I'm happy to approve

@ErikSchierboom Yes, I would also prefer these "integration tests" but that's for another time.