Twenty Fourteen: remove unneeded `.single-attachment` body class selectors, props iamtakashi. Fixes #25541, see #25506.

git-svn-id: https://develop.svn.wordpress.org/trunk@25737 602fd350-edb4-49c9-b593-d223f7449a82
Twenty Fourteen: remove unnecessary `no-sidebar` class value in front page template. Props iamtakashi, fixes #25543.

git-svn-id: https://develop.svn.wordpress.org/trunk@25738 602fd350-edb4-49c9-b593-d223f7449a82