Add the active model simulator.
user
```ruby
class Udongo::ActiveModelSimulator
  extend ActiveModel::Naming
  include ActiveModel::Conversion
  include ActiveModel::Validations

  def initialize(attributes = {})
    attributes ||= {}
    attributes.each do |name, value|
      send("#{name}=", value)
    end
  end

  def persisted?
    false
  end

  # This method exists so the related factory tests pass
  def save!
    valid?
  end
end
```
assistant