remove global box-sizing attribute which caused issues on front end of site for some users

git-svn-id: https://plugins.svn.wordpress.org/yikes-inc-easy-mailchimp-extender/trunk@954343 b8457f37-d9ea-0310-8a92-e5e31aec5664
update read me to reflect changes

git-svn-id: https://plugins.svn.wordpress.org/yikes-inc-easy-mailchimp-extender/trunk@954344 b8457f37-d9ea-0310-8a92-e5e31aec5664