Improve changelog

Improve the comment field in content editor and change log list and details are refactored based on last comment thread on PR #1289

PS. the `app/resources/translations/pt/messages.pt.yml` change end of line from CRLF to LF
For now, `icon-user` is ok, but I think bolt can use a gravatar user images (so, it is another issue).

I'll change it.