Indicate version of rails in migration file

[jcamejo]

Hi Guys, thanks a lot for your effort on this gem.

To make it rails 5 compatible i think is necessary to set the rails version number in the migration file to avoid this message:

Directly inheriting from ActiveRecord::Migration is not supported. Please specify the Rails release the migration was written for:

I'm copying this message here as a reminder, i will try to make a pull request soon.

Kind regards.

[kfrz]

If anyone's finding this and needs a solution - simply update the migration file with the rails version. I.e., Rails 5.1 would look like:

class CreateImpressionsTable < ActiveRecord::Migration[5.1]
...
end