Identiy tests that operate on arrays
Test to reproduce #57

JSON objects have same k/v pairs in different order and inside an array.
JSONDiff uses it's own equals method to compare arrays and objects

Two `JSONObject`'s with same key-value pairs but in a different order are still equal. And two arrays containing these respective objects are equal as well.

For now we are using the string representations of these objects for equality comparison since they sort the keys alpha-numerically but it is potentially a performance issue.

Fixes #57