Correct serialize/synchronize protocol definitions for v2+

[LeeCampbell]

http://www.introtorx.com/content/v1.0.10621.0/04_CreatingObservableSequences.html#ObservableCreate

The Create method is also preferred over creating custom types that implement the IObservable interface. There really is no need to implement the observer/observable interfaces yourself. Rx tackles the intricacies that you may not think of such as thread safety of notifications and subscriptions.

This is not entirely true as of v2.0