Changes breakout code to handle the new message format

.../imports/api/breakouts/server/handlers/breakoutJoinURL.js

...l5/imports/api/meetings/server/modifiers/removeMeeting.js

...ebutton-html5/imports/ui/components/nav-bar/component.jsx

...ml5/imports/ui/components/notifications-bar/container.jsx

...mports/ui/components/whiteboard/slide-controls/service.js