Add link to github

git-svn-id: https://plugins.svn.wordpress.org/ttt-crop/trunk@1002583 b8457f37-d9ea-0310-8a92-e5e31aec5664
add black image bug message


git-svn-id: https://plugins.svn.wordpress.org/ttt-crop/trunk@1002593 b8457f37-d9ea-0310-8a92-e5e31aec5664