add notification tab to settings modal

bigbluebutton-html5/client/stylesheets/bbb-icons.css

...button-html5/imports/ui/components/settings/component.jsx

...ui/components/settings/submenus/application/component.jsx

...i/components/settings/submenus/notification/component.jsx

...html5/imports/ui/components/settings/submenus/styles.scss

...st-content/user-participants/user-list-item/component.jsx

...st-content/user-participants/user-list-item/container.jsx

...r-participants/user-list-item/user-dropdown/component.jsx

bigbluebutton-html5/private/config/settings.yml

bigbluebutton-html5/private/locales/en.json

bigbluebutton-html5/public/fonts/BbbIcons/bbb-icons.woff

...luebutton-html5/public/resources/sounds/bbb-handRaise.mp3