Twenty Eleven: Add border styles to images so we can better style linked...

Twenty Eleven: Add border styles to images so we can better style linked images on :focus; includes updates to editor styles and improvements to Image Post styles; See #17524


git-svn-id: https://core.svn.wordpress.org/trunk@18132 1a063a9b-81f0-0310-95a4-ce76da25c4cd