Update the way the CF7->id() is accessed in the admin, for saving post meta data.

git-svn-id: https://plugins.svn.wordpress.org/contact-form-7-success-page-redirects/trunk@1004942 b8457f37-d9ea-0310-8a92-e5e31aec5664
Update readme.txt

git-svn-id: https://plugins.svn.wordpress.org/contact-form-7-success-page-redirects/trunk@1004944 b8457f37-d9ea-0310-8a92-e5e31aec5664