``sum`` method returns array with invalid C/F-contiguous flags

``` python
>>> x = np.random.random((5, 3))
>>> y = x.sum(0)
>>> print y.flags
  C_CONTIGUOUS : False
  F_CONTIGUOUS : False
  OWNDATA : True
  WRITEABLE : True
  ALIGNED : True
  UPDATEIFCOPY : False
>>> print y.strides, y.dtype
(8,) float64
```

This still works in 1.5.1.  Broken on the latest Git HEAD.

It affects all reductions of ndarray objects.
