Fix tests, active_authorizer shouldn't include blank values

Fix for a test failing after: 00ff0a67

railties/test/application/configuration_test.rb

@@ -361,7 +361,7 @@ def index
 
       assert_equal ActiveModel::MassAssignmentSecurity::WhiteList,
                    ActiveRecord::Base.active_authorizers[:default].class
-      assert_equal [""], ActiveRecord::Base.active_authorizers[:default].to_a
+      assert_equal [], ActiveRecord::Base.active_authorizers[:default].to_a
     end
 
     test "registers interceptors with ActionMailer" do