WIP: add stream name to event

[Braitenberg]

so that we can change the class names while maintaining the internal naming of an event

[lvonk]

What is the rationale behind stream_name? An event is not a stream (which is a series of events).

[Braitenberg]

i don't think we should do this, since it adds a layer of indirection when deserializing events. The difference with activerecord table names is that there, you never need to infer the class name from the table name. In our case, we would need some kind of lookup table to find the class corresponding with the overwritten event type.
This would also make it harder to debug, because you don't directly know which event name in de database corresponds with which class.

@lvonk let me know what you think