Add to_dict method to modelclass

[tarunamasa]

This pull request adds a to_dict method to the modelclass function. The to_dict method converts an instance of the class to a dictionary representation. This can be useful for serialization or other operations that require a dictionary representation of the object.

[justinpolygon]

Hey @tarunamasa, can you give me an example of how you're using this with the client? We might want to update the examples too.