Remove support for get_field_by_name for < 1.8
Remove support for get_field_by_name for < 1.8

daniell/django-import-export,daniell/django-import-export,jnns/django-import-export,bmihelac/django-import-export,django-import-export/django-import-export,daniell/django-import-export,django-import-export/django-import-export,bmihelac/django-import-export,jnns/django-import-export,bmihelac/django-import-export,daniell/django-import-export,django-import-export/django-import-export,jnns/django-import-export,jnns/django-import-export,bmihelac/django-import-export,django-import-export/django-import-export