AttributesDictionary Json Converter is not reversible

[TimPurdum]

The AttributesDictionaryConverter was written primarily to support serialization to JavaScript. Because of that, the Write output format is not a normal Dictionary/Object, and it is not supported by the Read method.

The custom Write logic probably really belongs in the TypeScript layer. However, it stores .NET type information, and might need to stay where it is (DateTimes, for example, once serialized, look like strings, and we lose the strong typing). Either way, the Read method should support both dictionary/object and array formats, so that it can accept data from different sources.

[TimPurdum]

Closed with #349