fixed the url scheme problem

- no use of $_SERVER["HTTPS"]

$_SERVER["HTTPS"] might be 'off' on IIS.
http://php.net/manual/ja/reserved.variables.server.php

git-svn-id: http://plugins.svn.wordpress.org/thin-out-revisions/trunk@1001654 b8457f37-d9ea-0310-8a92-e5e31aec5664
Version 1.7.2

git-svn-id: http://plugins.svn.wordpress.org/thin-out-revisions/trunk@1001656 b8457f37-d9ea-0310-8a92-e5e31aec5664