Rake task to test Hale spec


I've added a task that downloads the hale spec from github and tries to roundtrip the examples.

Current results:
10 examples in that repository , 4 of them has JSON errors and can not even be parsed, 1 breaks the serialization code (type exception), 4 not pass the test and  1 pass the test.

I think this task is important to check both the spec is sane (JSON errors WTF!) and have a very small ensurance that the code is able to match the spec.

This PR includes #28 or I was hitting many ruby errors. Please merge that one first @chad-medi @cabbott @sheavalentine-mdsol