Fix "(invalid)" markup in summary view

The markup of "(invalid)" is rendered as plain text due to the fact that
they are produced in a ERB tag without the use of `String#html_safe` or
the `raw` method.
Merge pull request #1570 from zhangsu/summary_group_invalid_span

Fix "(invalid)" markup in summary view
Merge branch 'master' of git://github.com/MarkUsProject/Markus into sass-r3
Centralized notes dialog styling.