Updating contributors and author image to Z logo

git-svn-id: https://plugins.svn.wordpress.org/scan-to-login/trunk@912494 b8457f37-d9ea-0310-8a92-e5e31aec5664
Updated readme.txt

git-svn-id: https://plugins.svn.wordpress.org/scan-to-login/trunk@912496 b8457f37-d9ea-0310-8a92-e5e31aec5664