WP_HTTP: Funnel all redirect requests through WP_HTTP::request() via wp_remote_request() to ensure that the proper transport is chosen for redirects. 
This change also moves PHP Streams from redirecting internally, to us handling the redirections in PHP, which brings a more consistent behaviour between transports.
Fixes #23682



git-svn-id: http://core.svn.wordpress.org/trunk@23603 1a063a9b-81f0-0310-95a4-ce76da25c4cd