Windows Server IIS web.config support

Hi,

I'm not sure this is the right place for this, but here goes:
It bugs me that WP-Super-Cache lacks IIS web.config support, even though this support is available in WordPress Core through the `$is_iis7()` boolean. What can I do to fix that? :) It'll be horror to write the appropriate web.config rewrite rules, I know, but I think it'll help a lot of WordPress users hosted on Windows Server IIS.

I've successfully converted the generated .htaccess file and rules to web.config, which works great.

Start by tracing where WP-Super-Cache generates its .htaccess rules and compare that path with WordPress Core's `$is_iis7()` boolean. Use the reported converted web.config rules as the reference, and consider the work complete when equivalent IIS rules are generated for Windows Server users.

Written by the indexing model from the issue text.