Update the text for the about page, so translators can get started. Design is in flux.

props nacin, markjaquith, jorbin, jenmylo.
see #25603.

Built from https://develop.svn.wordpress.org/trunk@25832


git-svn-id: http://core.svn.wordpress.org/trunk@25744 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Check if background core updates are supported on about.php.

see #25603, #22704.

Built from https://develop.svn.wordpress.org/trunk@25833


git-svn-id: http://core.svn.wordpress.org/trunk@25745 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Remove redundant code. see #25603, #22704, [25833].

Built from https://develop.svn.wordpress.org/trunk@25834


git-svn-id: http://core.svn.wordpress.org/trunk@25746 1a063a9b-81f0-0310-95a4-ce76da25c4cd