Automate migration of ActiveRecord::Base to ApplicationRecord

The rails upgraded already does this kind of "mirgation" with strong params, it would be nice If we can add this other "migration" for going from `Rails 4.2` Rails `5-0`

```
class ApplicationRecord < ActiveRecord::Base
self.abstract_class = true
end
```

And then update all of your models to inherit from ApplicationRecord instead of ActiveRecord::Base. The only class that inherits from ActiveRecord::Base will be ApplicationRecord.