Iterator for Twisted N1QL request is broken

TypeError: iter() returned non-iterator of type 'list'

I suspect this is due to BatchedRowMixin returning a list on it's _iter_ function rather than the list's _iter_:

ie.
```
def _iter_(self):
"""
Iterate over the rows in this resultset
"""
return self.__rows
```

should be:

```
def _iter_(self):
"""
Iterate over the rows in this resultset
"""
return self._rows.iter_()
```

I'd submit a fix but I haven't looked at this enough to know if it would break BatchedView. Also the Async N1QL documentation could be a bit better.