here is a somewhat hacky way to force use an empty selector where "#"
was used as a selector before

closes #7372

closes #7356

closes #7354

See http://rubocop.readthedocs.io/en/latest/cops_rails/#railshttppositionalarguments.

It only applies to Rails >= 5

closes #7353

Thor was upgraded again in #7345, but there are still "warnings" looking
like errors when using "db:migrate" for example. So lets pin it until it is
safe to upgrade.

closes #7351

fixes #7317

closes #7322

closes #7348

And update config for new/updated cops.