new stager reverse_http_proxy_pstore

This does the same as windows stager reverse_http but it also tries to obtain authentication from Windows Protected Storage (used in Win XP and Win Server 2003, IE Version 4 to 6) and passes them to the preconfigured proxy server via InternetConnect function.

If no authentication is found or there is no preconfigured proxy server, this should work just like reverse_http.
Feels like it should block.  If it doesn't get fixed before landing, it never will.