Exclude default roles from custom_permissions

It makes no sense to duplicate a role that can access everything,
and another that shouldn't access anything.

core/app/models/spree/permission_set.rb

@@ -13,6 +13,7 @@ class PermissionSet < Spree::Base
  scope :custom_permissions, -> {
  where.not(id: display_permissions)
  .where.not(id: management_permissions)
+ .where.not(set: ['Spree::PermissionSets::SuperUser', 'Spree::PermissionSets::DefaultCustomer'])
  }
  end
 end