Twenty Thirteen: better back compat handling by moving version compare before the include to avoid loading the file altogether. Also prevent Customizer views. Props obenland, closes #23819.

git-svn-id: http://core.svn.wordpress.org/trunk@23837 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Twenty Thirteen: back compat file PHPDoc updates, thanks DrewAPicture for the nudge. See #23819.

git-svn-id: http://core.svn.wordpress.org/trunk@23838 1a063a9b-81f0-0310-95a4-ce76da25c4cd