CI: build pandas on windows (appveyor)
Here is a collection of build scripts/tools for windows:
a nice conda recipe:
https://github.com/rmcgibbo/python-appveyor-conda-example/blob/master/appveyor.yml

https://github.com/pydata/pandas/tree/master/scripts/windows_builder

I have found many confusing explanations/suggestion on the web on how to build python extensions on windows 32/64 bit. The following is very simple to build from master.

Follow the instructions on the following link to build on windows with a binary compat to the existing python. Bascially.

http://pybytes.com/pywavelets/dev/preparing_windows_build_environment.html#installing-windows-sdk-c-c-compiler

Essentially:
- download the Microsoft SDK (you need the 64-bit one of you are on a 64-bit machine, even if you are going to want to build 32-bit builds); this is just the install kit. I used http://www.slysoft.com/en/virtual-clonedrive.html to mount the `.iso` and install it
- open the CMD Shell (installed onto the start menu)
- set the env variables (I just copy pasted, but you can make a bat file if you want). for either 32 or 64 bit.

you can then just

```
c:\python27\python.exe setup.py build_ext --inplace
c:\python27\scripts\nosetests pandas
```
