Fixing tests for Python 2 (using StringIO instead of io module).
Fixing tests for Python 2 (using StringIO instead of io module).

fabrique/django-sortedm2m,gradel/django-sortedm2m,fabrique/django-sortedm2m,gradel/django-sortedm2m,fabrique/django-sortedm2m,gregmuellegger/django-sortedm2m,gradel/django-sortedm2m,gregmuellegger/django-sortedm2m,gregmuellegger/django-sortedm2m