Accuracy Core Package Test Coverage Managed by coverall.io

[hemalvarambhia]

We need to get the accuracy core package tests to have their coverage computed by coveralls.io. This replaces #106 as that issue has become a bit too big.

[hemalvarambhia]

@SergeStinckwich An update on this - I'm splitting out the test for testDataTree to its own class & separating out the assertions to their own test methods. That way it's easy to tell which failed. Suggests the methods does a lot too (code smell?)!

[hemalvarambhia]

Now, as you can see in the travis failure, testExtractFromResultsWhichOnlyOne is failing and not testDataTree has mentioned in my last comment.

[hemalvarambhia]

@SergeStinckwich The PMAccuracy class is used in the Function-Fit package, where it is the parent of PMGAAccuracy. I'd like to replace the two remaining calls to argument in the latter with argumentWith: until we can find a way to use the reflection-based code in findKey safely.