Add module for windows package management via chocolatey

Work in progress - this PR is a stub to start discussion and gauge interest.
http://chocolatey.org for information.
Note - chocolatey will be replaced by [OneGet](https://github.com/OneGet/oneget) once powershell v5 comes out, but who wants to wait for that? ;-)
Note2 - this is my first ansible module of any sort, after spending a bit of time playing with it to provision a windows 2012 server in AWS to use as the basis for AMI baking. I've got no idea how to go about writing test automation for this, so guidance and steers there would be appreciated.