Fix to center location pointer

git-svn-id: https://plugins.svn.wordpress.org/very-simple-google-maps/trunk@957583 b8457f37-d9ea-0310-8a92-e5e31aec5664
fix readme text

git-svn-id: https://plugins.svn.wordpress.org/very-simple-google-maps/trunk@957586 b8457f37-d9ea-0310-8a92-e5e31aec5664