fixed rel.relationship(target) to default None model

Hi again,

This time i found about when trying to "inflate" relationships with the default model (None), for me the fix could be that simple like return the relationship, but maybe you want to try a "default" inflate taking the properties of the relationship just as the type of it, or taking all properties of the relationship as StringProperties, is up to you.

This is what i was trying to do:

```python
  def _parse_entity_relationships(self, k, v):
        rv = {}
        current_node = self._get_current()
        rel = getattr(current_node, k)
        rv['direction'] = rel.definition['direction']
        for t in rel.all():
            rel_inst = rel.relationship(t)
        ...     
        return rv
```