custom attributes readme issue

[raycohen]

in the Custom Serializers section of the readme, as written, Person.new.attributes will error on both options and scope not being defined.

It seems like the fix might be to move both methods full_name and attribtues into an ActiveModel::Serializer class rather than an ActiveRecord::Base. However then I get wrong number of arguments on the super(options) line, and full_name needs to be changed to use object.first_name.