DOC: cython example from docs is not working in Windows
The last example in the "Enhancing performance" docs on cython (http://pandas.pydata.org/pandas-docs/dev/enhancingperf.html#more-advanced-techniques) is failing on Windows. 
When I run the example I get a `ValueError: Buffer dtype mismatch, expected 'Py_ssize_t' but got 'long'` error:

```
In [18]: %timeit apply_integrate_f_wrap(df['a'].values, df['b'].values, df['N'].values)
---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
<ipython-input-18-1222be30cf93> in <module>()
----> 1 get_ipython().magic(u"timeit apply_integrate_f_wrap(df['a'].values, df['b'].values, df['N'].values)")

c:\users\vdbosscj\scipy\ipython\IPython\core\interactiveshell.pyc in magic(self, arg_s)
   2184         magic_name, _, magic_arg_s = arg_s.partition(' ')
   2185         magic_name = magic_name.lstrip(prefilter.ESC_MAGIC)
-> 2186         return self.run_line_magic(magic_name, magic_arg_s)
   2187 
   2188     #-------------------------------------------------------------------------

c:\users\vdbosscj\scipy\ipython\IPython\core\interactiveshell.pyc in run_line_magic(self, magic_name, line)
   2105                 kwargs['local_ns'] = sys._getframe(stack_depth).f_locals
   2106             with self.builtin_trap:
-> 2107                 result = fn(*args,**kwargs)
   2108             return result
   2109 

c:\users\vdbosscj\scipy\ipython\IPython\core\magics\execution.pyc in timeit(self, line, cell)

c:\users\vdbosscj\scipy\ipython\IPython\core\magic.pyc in <lambda>(f, *a, **k)
    191     # but it's overkill for just that one bit of state.
    192     def magic_deco(arg):
--> 193         call = lambda f, *a, **k: f(*a, **k)
    194 
    195         if callable(arg):

c:\users\vdbosscj\scipy\ipython\IPython\core\magics\execution.pyc in timeit(self, line, cell)
   1011             number = 1
   1012             for _ in range(1, 10):
-> 1013                 if timer.timeit(number) >= 0.2:
   1014                     break
   1015                 number *= 10

C:\Anaconda\envs\devel\lib\timeit.pyc in timeit(self, number)
    193         gc.disable()
    194         try:
--> 195             timing = self.inner(it, self.timer)
    196         finally:
    197             if gcold:

<magic-timeit> in inner(_it, _timer)

C:\Users\vdbosscj\.ipython\cython\_cython_magic_fa1038e4eeefba896480cf749d6fc60d.pyd in _cython_magic_fa1038e4eeefba896480cf749d6fc60d.apply_integrate_f_wrap (C:\Users\vdbosscj\.ipython\cython\_cython_magic_fa1038e4eeefba896480cf749d6fc60d.c:1762)()

ValueError: Buffer dtype mismatch, expected 'Py_ssize_t' but got 'long'
```
