Updating short description

git-svn-id: https://plugins.svn.wordpress.org/zm-ajax-login-register/trunk@855319 b8457f37-d9ea-0310-8a92-e5e31aec5664
Updating readme

git-svn-id: https://plugins.svn.wordpress.org/zm-ajax-login-register/trunk@855320 b8457f37-d9ea-0310-8a92-e5e31aec5664