Fix alignment and borders of plugin/theme updates on the Updates screen.

props morganestes, ocean90.
see #26699, for trunk.

Built from https://develop.svn.wordpress.org/trunk@26935


git-svn-id: http://core.svn.wordpress.org/trunk@26816 1a063a9b-81f0-0310-95a4-ce76da25c4cd
TinyMCE: improve handling of Read More and Nextpage tags. See #24067, fixes #16239.
Built from https://develop.svn.wordpress.org/trunk@26941


git-svn-id: http://core.svn.wordpress.org/trunk@26821 1a063a9b-81f0-0310-95a4-ce76da25c4cd
TinyMCE: add/remove the 'alignnone' class when aligning images without captions. See #24067.
Built from https://develop.svn.wordpress.org/trunk@26942


git-svn-id: http://core.svn.wordpress.org/trunk@26822 1a063a9b-81f0-0310-95a4-ce76da25c4cd