DEV: resolve Rails/ReversibleMigrationMethodDefinition errors (#110)

Author: tyb-talks

db/migrate/20190724055909_move_to_managed_authenticator.rb

@@ -22,4 +22,8 @@ def up
     DO NOTHING
     SQL
   end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
 end