Updated compatibility and fixed styling to fit WP

git-svn-id: https://plugins.svn.wordpress.org/wp-big-login/trunk@981599 b8457f37-d9ea-0310-8a92-e5e31aec5664
fixed screenshots

git-svn-id: https://plugins.svn.wordpress.org/wp-big-login/trunk@981602 b8457f37-d9ea-0310-8a92-e5e31aec5664