Always show Background Image section heading and the opening table tag on Custom Background screen, to make in consistent with Custom Header and avoid broken markup.

props obenland.
fixes #26731.
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git-svn-id: http://core.svn.wordpress.org/trunk@26761 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Update the readme to 3.9. props kworthington. fixes #26739.
Built from https://develop.svn.wordpress.org/trunk@26879


git-svn-id: http://core.svn.wordpress.org/trunk@26762 1a063a9b-81f0-0310-95a4-ce76da25c4cd