For all instances where a `Contract` instance is serialized using `JSON.stringify`, the `logger` property was being stringified and written to logs and contract artifact files.
Add Serializer class that allows ignoring of class properties during serialization when using `JSON.stringify`.
NOTE: The `Serializer` relies on TypeScript’s decorators which are still listed as experimental (requiring the necessary compiler flag) despite being around for several years. Decorators are a stage 2 proposal for JavaScript.
