Generator: Module missing for Model in mountable engine

If I create a new Model with i.e. `rails g Model Widged title:string` in a ***mountable*** rails engine the resulting factory gets only partially namespaced/modularized:

```ruby
FactoryGirl.define do
  factory :widged_factory_widged, :class => 'Widged' do
    title "MyString"
  end
end
```
I would expect something like this:
```ruby
FactoryGirl.define do
  factory :widged_factory_widged, :class => WidgedFactory:Widged  do
    title "MyString"
  end
end
```
If you need a sample mountable rails engine to verify this I'll happyily provide one.