Django-composite-field

* Add empty `flatchoices` attribute to `CompositeField`

* Add `primary_key=False` to `CompositeField`

* Fix `Model.full_clean()` error when using a `CompositeField`
* Add `get_col` method to `LocalizedField` making it possible
to use it in a `QuerySet`.

* Fix `ModelForm` for models with a `CompositeField`
* Implement `current(_with_default)` and `all` property of
`LocalizedField`

* Fix composite proxy `__eq__` method when comparing against
non composite values
* Fix translation fallback
* Fix `verbose_name` as positional argument in `LocalizedField`

* Fix Python 3.2 compatibility
* Composite field as virtual field in model