version bump and field wizard fix

git-svn-id: https://plugins.svn.wordpress.org/mailchimp-for-wp/trunk@864672 b8457f37-d9ea-0310-8a92-e5e31aec5664
updated readme to include changelog

git-svn-id: https://plugins.svn.wordpress.org/mailchimp-for-wp/trunk@864675 b8457f37-d9ea-0310-8a92-e5e31aec5664