scoped models serialize into invalid xml

The ActiveRecord::XmlSerializer creates invalid xml when serializing models within a scope.

>> puts Myscope::Mymodel.first.to_xml
<myscope/mymodel>
...
</myscope/mymodel>

This xml is invalid because you are not allowed slashes in a node name. The invalid node name is caused by the way XmlSerializer converts a model's class name into the xml root string

record.class.to_s.underscore

( in xml_serializer.rb on lines 180 and 223 )

I offer this as a possible fix

record.class_name.underscore