move slide position data into its own collection

...orts/api/presentation-pods/server/utils/isPodPresenter.js

...rts/api/presentations/server/modifiers/addPresentation.js

bigbluebutton-html5/imports/api/slides/index.js

bigbluebutton-html5/imports/api/slides/server/helpers.js

...on-html5/imports/api/slides/server/methods/switchSlide.js

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

...ton-html5/imports/api/slides/server/modifiers/addSlide.js

.../imports/api/slides/server/modifiers/addSlidePositions.js

...imports/api/slides/server/modifiers/changeCurrentSlide.js

...-html5/imports/api/slides/server/modifiers/clearSlides.js

...ts/api/slides/server/modifiers/clearSlidesPresentation.js

...-html5/imports/api/slides/server/modifiers/resizeSlide.js

bigbluebutton-html5/imports/api/slides/server/publishers.js

...on-html5/imports/ui/components/presentation/component.jsx

...on-html5/imports/ui/components/presentation/container.jsx

...utton-html5/imports/ui/components/presentation/service.js

...n-html5/imports/ui/components/subscriptions/component.jsx

bigbluebutton-html5/private/config/settings.yml