Show a space as thousands separator for comments count when setting from js,...

Show a space as thousands separator for comments count when setting from js, hide ajax throbber when QE returns an error, see#8227 fixes #8225

git-svn-id: https://core.svn.wordpress.org/trunk@9726 1a063a9b-81f0-0310-95a4-ce76da25c4cd