3.0 major update; see readme.txt

git-svn-id: https://plugins.svn.wordpress.org/seo-image/trunk@1050796 b8457f37-d9ea-0310-8a92-e5e31aec5664
removed screenshots

git-svn-id: https://plugins.svn.wordpress.org/seo-image/trunk@1050798 b8457f37-d9ea-0310-8a92-e5e31aec5664
added tags

git-svn-id: https://plugins.svn.wordpress.org/seo-image/trunk@1050800 b8457f37-d9ea-0310-8a92-e5e31aec5664