Twenty Twelve: show featured image in single page views. Fixes #22943, props MikeHansenMe.

git-svn-id: https://core.svn.wordpress.org/trunk@23471 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Twenty Twelve: better layout for floated image captions. Fixes #23147.

git-svn-id: https://core.svn.wordpress.org/trunk@23472 1a063a9b-81f0-0310-95a4-ce76da25c4cd