Fix a vulnerability which allows to avoid CAPTCHA validation.

git-svn-id: https://plugins.svn.wordpress.org/contact-form-7/trunk@865491 b8457f37-d9ea-0310-8a92-e5e31aec5664
Update jquery.form.js to 3.50.0-2014.02.05.

git-svn-id: https://plugins.svn.wordpress.org/contact-form-7/trunk@865500 b8457f37-d9ea-0310-8a92-e5e31aec5664
Ready for 3.7.2 release.

git-svn-id: https://plugins.svn.wordpress.org/contact-form-7/trunk@865524 b8457f37-d9ea-0310-8a92-e5e31aec5664