Introduce Hanami::Interactor properly

[ariejan]

See http://www.rubydoc.info/gems/hanami-utils/Hanami/Interactor/Interface, it's part of Uncle Bob's Clean Architecture idea and makes a lot of sense. Firefly does not use Interactors, but it should.

[volgorean]

def call
   ItemRepository.transaction do
   @item = ItemRepository.find_by_content(@item) || ItemRepository.persist(@item)
   LinkHtmlTitleWorker.perform_async(@item.id)
end

Do we want to create a worker and perform another title fetch if @item isn't a new Object?
It's probably not an issue just making sure that was intended.

[ariejan]

@volgorean actually that was intentional. If I saved a URL like 10 months ago, and I'm saving it again now, I'd like the title to be updated.

[volgorean]

Good point.