fixed generator specs and added migration version

[emptyflask]

Rails 5.x expects migrations to subclass ActiveRecord::Migration[5.x]

[seuros]

Thank you @emptyflask for this fix.
It will break in rails 4.2 :(

let me think about a solution

[emptyflask]

Will it? Under Rails 4, the version should just be nil. Or will it fail for some other reason?

[seuros]

You sure ? I think it will be ActiveRecord::Migration4

[seuros]

Nevermind. It works 👍