Delete org broken

causes error
```
File '/home/fki/pyenv/src/ckan/ckan/controllers/group.py', line 458 in delete

  self._action('group_delete')(context, {'id': id})

File '/home/fki/pyenv/src/ckan/ckan/logic/__init__.py', line 323 in wrapped

  return _action(context, data_dict, **kw)

File '/home/fki/pyenv/src/ckan/ckan/logic/action/delete.py', line 261 in organization_delete

  return _group_or_org_delete(context, data_dict, is_org=True)

File '/home/fki/pyenv/src/ckan/ckan/logic/action/delete.py', line 223 in _group_or_org_delete

  for pkg in group.active_packages().all():

AttributeError: 'Group' object has no attribute 'active_packages'
```