Translating a delegated enum

```
Class Student
  delegate :type, to: school, prefix: :true
end

class School
  include SimpleEnum::Mongoid
  as_enum :type, [:business, :technical]
end

te(@student, school_type) # Doesn't seem to work
```

Taking care of delegated stuff can become pretty nasty I suppose... here the translation should propagate from the Student to the School model.
