Add support to custom version association class

[sobrinho]

Fixes #45

[sobrinho]

This is a draft, still needs to be tested.

[sobrinho]

@westonganger ping :)

[westonganger]

@sobrinho I don't see any documentation for this. Can you write some in the readme. Then it should be easier to review.

[sobrinho]

@westonganger added a small example to README.md.

Is that what you are looking for?

This is the same as papertrail has for the version class, we have a use case like this :

class Product < ApplicationRecord
  has_paper_trail(
    versions: { class_name: "ProductVersion" }, # papertrail has this native
    version_associations: { class_name: "ProductVersionAssociation" } # this PR will add this one
  )
end

[westonganger]

Ok looks alright. Can you also add a changelog entry for this

[sobrinho]

@westonganger added

[westonganger]

Sorry to keep asking for more. But can you actually write one or two tests for this feature?

[westonganger]

@sobrinho ping

[sobrinho]

@westonganger will do today or tomorrow

[sobrinho]

@westonganger can you review this again?

I had to change the implementation a little bit and I'm not 100% sure this is in the right direction.

[sobrinho]

Even if I remove the PaperTrailAssociationTracking::VersionConcern entirely, specs still passes.

So, looks like after this we are decoupling Version and VersionAssociation entirely.