Adding import_filter to hash

[formigarafa]

I have have created a branch (formigarafa#2) to add import_filters to a hash filter.

hash :a_hash do
  import_filters AnotherInteractor
end

I just couldn't figure where to put some tests and keep the same format used.
I would really appreciate If anyone could take a look at the feature to give me some help with that.

Thanks.