Feature/Versionable mixin

[rhyslbw]

Background

• Currently versioning support for events is hardcoded
• It's also important for other serializables, but eventVersion is specific and needs to be either made generic or made configurable.
• This trait should be an option for any Struct given the feature is just to provide a transformation from one structure to another.

  Options

• configurable - Where would this be done?
• schemaVersion
• structVersion
• version

[rhyslbw]

I feel we should just pick a generic name and avoid the technical debt of a configurable option. My vote is simply for version unless there's a good reason not to

[DominikGuzei]

we cannot pick version since that collides with ES version. This really is more like a schema version. Another option could be apiVersion

[rhyslbw]

In that case I vote for schemaVersion

[darko-mijic]

schemaVersion makes more sense than apiVersion to me also.

[rhyslbw]

https://github.com/meteor-space/messaging/pull/29