fix button outlines and clean up video button and video preview

...utton-html5/imports/ui/components/actions-bar/styles.scss

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

...n-html5/imports/ui/components/video-preview/component.jsx

...s/ui/components/video-provider/video-button/component.jsx

...rts/ui/components/video-provider/video-button/styles.scss