Inconsistent comparison between datetime and series of datetime
similar to #3416 (also failing in 0.11)

Using pandas 0.10.1 and numpy 1.6.1:

```
>>> import pandas; import numpy
>>> s = pandas.Series(pandas.date_range('2013-01-01', periods=3))
>>> d = numpy.datetime64('2013-01-02')
>>> s > d
0    False
1    False
2     True
>>> d < s
0    True
1    True
2    True
>>> s.dtype
dtype('datetime64[ns]')
>>> d.dtype
dtype('datetime64[us]')
```

All other comparison operators also give expected results with operands (s,d), and seem to compare them as unscaled integers when the order is (d,s).
