Doesn't build on windows
pandas cannot be installed on Windows, neither with pip or easy_install:

```
$ pip install pandas
...
...
running build_ext
building 'pandas._tseries' extension
creating build\temp.win-amd64-2.7
creating build\temp.win-amd64-2.7\Release
creating build\temp.win-amd64-2.7\Release\pandas
creating build\temp.win-amd64-2.7\Release\pandas\src
C:\Program Files (x86)\Microsoft Visual Studio 9.0\VC\BIN\cl.exe /c /nologo /Ox /MD /W3 /GS- /DNDEBUG -IC:\Python27\lib\site-packages\numpy\core\include -IC:\Python27\include -IC:\Python27\PC /Tcpandas\src\tseries.c /Fobuild\temp.win-amd64-2.7\Release\pandas\src\tseries.obj
tseries.c
c:\python27\include\pyconfig.h(68) : fatal error C1083: Cannot open include file: 'io.h': No such file or directory
error: command '"C:\Program Files (x86)\Microsoft Visual Studio 9.0\VC\BIN\cl.exe"' failed with exit status 2
```
