pandas query is broken
This works:

```
(df1.col1/(df1.col1+df1.col2)).plot(ylim=[0,.1])
```

But this fails (even with `engine`/`parser` set to `python`):

```
df1.query('col1/(col1+col2)').plot(ylim=[0,.1])
```

with traceback:

```
C:\Python\Python27\lib\site-packages\pandas\core\frame.pyc in query(self, expr, **kwargs)
   2053 
   2054         try:
-> 2055             return self.loc[res]
   2056         except ValueError:
   2057             # when res is multi-dimensional loc raises, but this is sometimes a

C:\Python\Python27\lib\site-packages\pandas\core\indexing.pyc in __getitem__(self, key)
   1196             return self._getitem_tuple(key)
   1197         else:
-> 1198             return self._getitem_axis(key, axis=0)
   1199 
   1200     def _getitem_axis(self, key, axis=0):

C:\Python\Python27\lib\site-packages\pandas\core\indexing.pyc in _getitem_axis(self, key, axis)
   1330                     raise ValueError('Cannot index with multidimensional key')
   1331 
-> 1332                 return self._getitem_iterable(key, axis=axis)
   1333 
   1334             # nested tuple slicing

C:\Python\Python27\lib\site-packages\pandas\core\indexing.pyc in _getitem_iterable(self, key, axis)
    940     def _getitem_iterable(self, key, axis=0):
    941         if self._should_validate_iterable(axis):
--> 942             self._has_valid_type(key, axis)
    943 
    944         labels = self.obj._get_axis(axis)

C:\Python\Python27\lib\site-packages\pandas\core\indexing.pyc in _has_valid_type(self, key, axis)
   1278 
   1279                 raise KeyError("None of [%s] are in the [%s]" %
-> 1280                                (key, self.obj._get_axis_name(axis)))
   1281 
   1282             return True

KeyError: 'None of [2015-07-01 00:00:36    1.000000\n2015-07-01 00:01:36    1.000000\n2015-07-01 00:02:36    1.000000\n2015-07-01 00:03:36    1.000000\n2015-07-01 00:04:36    1.000000\n2015-07-01 00:05:36    1.000000\n2015-07-01 00:06:37    1.000000\n2015-07-01
 ...
14:33:57    0.031360\n2015-11-06 14:34:57    0.031348\n2015-11-06 14:35:57    0.031365\ndtype: float64] are in the [index]'   
```
