[web] write css_class to attrs on rendering and not on button creation
Because css_class attribute may be overriden by bootstrap after button creation and this
modification has to be taken into account.
closes #5457548
# -*- coding: utf-8 -*-
# copyright %(year)s %(author)s, all rights reserved.
# contact %(author-web-site)s -- mailto:%(author-email)s
#
%(long-license)s
"""%(distname)s repository side views, usually for notification"""