port flash code to js and implement initial work in zoom

...tton-html5/imports/api/slides/server/methods/zoomSlide.js

...omponents/presentation/presentation-overlay/component.jsx

...i/components/presentation/presentation-toolbar/service.js

bigbluebutton-html5/imports/utils/slideCalcUtils.js

bigbluebutton-html5/imports/utils/slideViewModel.js