GetPathAny(), JsonArray(), JsonMap()

Adding 3 new methods:
- GetPathAny() is like GetPath(), but can also go through arrays

- JsonArray() and JsonMap() are like Array() and Map(), but they return arrays and maps with Json values, so you can interact with them more easily. This partially solves issue #25.
Actually I tried that at first, but one of the tests gave an error about converting []string to []interface{}, so it's not fully compatible.