Prevent the use of Feed Statistics as an open redirect.

git-svn-id: https://plugins.svn.wordpress.org/wordpress-feed-statistics/trunk@960868 b8457f37-d9ea-0310-8a92-e5e31aec5664
Changelog for version 4

git-svn-id: https://plugins.svn.wordpress.org/wordpress-feed-statistics/trunk@960869 b8457f37-d9ea-0310-8a92-e5e31aec5664