Merge pull request #145 from fge/master

Make JsonNode implement all of .isXxx() methods (2.2 material)
Fix #118
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Added failing test for object deserialization based on id
Merge pull request #151 from Airborn/master

Test case for #97
ArrayNode: make _children final

Simplifies quite a lot of code in the process.
ObjectNode: make _children final

Simplifies quite a lot of code in the process.