Fixing for compatibility with django 1.4.
Fixing for compatibility with django 1.4.

The field attname was being overwritten with the field name and losing the '_id' suffix for FKs.
This issue would break new models binded with simple history as they would have its historical model with the wrong field names for FKs.

treyhunner/django-simple-history,pombredanne/django-simple-history,luzfcb/django-simple-history,emergence/django-simple-history,emergence/django-simple-history,luzfcb/django-simple-history,pombredanne/django-simple-history,treyhunner/django-simple-history