adds slide controls and new bbb icons

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

...tations/server/methods/publishSwitchToNextSlideMessage.js

...ons/server/methods/publishSwitchToPreviousSlideMessage.js

...sentations/server/methods/publishSwitchToXSlideMessage.js

bigbluebutton-html5/imports/locales/en.json

...ton-html5/imports/ui/components/button/base/component.jsx

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

bigbluebutton-html5/imports/ui/components/button/styles.scss

...rts/ui/components/whiteboard/slide-controls/component.jsx

...rts/ui/components/whiteboard/slide-controls/container.jsx

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

...ports/ui/components/whiteboard/slide-controls/styles.scss

...utton-html5/imports/ui/stylesheets/variables/palette.scss

bigbluebutton-html5/package.json

bigbluebutton-html5/server/server.js