Added icon for WP4.0



git-svn-id: https://plugins.svn.wordpress.org/slider-captcha/trunk@979447 b8457f37-d9ea-0310-8a92-e5e31aec5664
Added sandro to contributors


git-svn-id: https://plugins.svn.wordpress.org/slider-captcha/trunk@979503 b8457f37-d9ea-0310-8a92-e5e31aec5664