Partial webcams grid improvements

...luebutton-html5/imports/ui/components/media/component.jsx

...luebutton-html5/imports/ui/components/media/container.jsx

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

...i/components/media/webcam-draggable-overlay/component.jsx

...rts/ui/components/video-provider/video-list/component.jsx

...ports/ui/components/video-provider/video-list/styles.scss

...s/video-provider/video-list/video-list-item/component.jsx

...ebutton-html5/imports/ui/stylesheets/variables/video.scss