Migrations shouldn't fail RuboCop checks - especially lint checks, such
as the nested method check. To avoid changing code in existing
migrations, add the magic comment to the top of each of them to skip
that file.
It will hold notification setting per group or per project. It will
allow get rid of notification level stored in Member model
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>