Updates for win_user module

(Resubmitting changes from https://github.com/ansible/ansible/pull/8945)

These changes allow for retrieving and updating all of the local user properties available in the *General* and *Member Of* tabs in Windows.  It fixes https://github.com/ansible/ansible/issues/8711 by allowing a group to be specified when creating a user.

![image](https://cloud.githubusercontent.com/assets/429563/4206711/932e16d4-384e-11e4-8bdb-959ff05c8e3b.png)

![image](https://cloud.githubusercontent.com/assets/429563/4206720/a6d49ed8-384e-11e4-96c6-cd780e4700b7.png)

The only backwards-incompatible changes are the following result fields that have been renamed:
* `user_name` is now `name`
* `user_fullname` is now `fullname`
* `user_path` is now `path`