Enable the YouTube embed checker by default.

git-svn-id: https://plugins.svn.wordpress.org/broken-link-checker/trunk@999136 b8457f37-d9ea-0310-8a92-e5e31aec5664
Replace the EmbedPlus banner with a new image.

git-svn-id: https://plugins.svn.wordpress.org/broken-link-checker/trunk@999137 b8457f37-d9ea-0310-8a92-e5e31aec5664