add shortcut to toggle presenter and overview mode
add shortcut to toggle presenter and overview mode

Crazy50/IsomorphicTalk,wilsaj/osm-talk-open-institute,tsmall/presentations,oliviertassinari/SplitMeBord,caffodian/django-react-crash-course,linclark/jsconf-last-call,metalabdesign/slerk-slidedeck,AgtLucas/spectacle,thepauleh/slides,hartmamt/builder-talk,linclark/spectacle,lewiscowper/npmlovesheffield,wilsaj/intro-to-josm,jamiepenney/app-quality-slides,lewiscowper/npm-basically-magic,SeeThruHead/es6pres,gdseller/spectacle,ALF-er/kharkivjs2015,kwangkim/spectacle,UmarMughal/spectacle,oliviertassinari/SplitMeBord,vcarrera/spectacle,asbjornenge/spectacle,zpao/spectacle,greising/spectacle,codemade/wmks-react,EdisonReklamebyraa/isolaBDRdk,codemade/wmks-flux,tikotzky/spectacle,Spy-Seth/spectacle,jimpick/spectacle,lowsky/spectacle,unbracketed/react-intro-talk,andrebeat/rust-presentation,revrng/spectacle,FormidableLabs/spectacle,rektide/webpush-away-deck,htmelvis/spectacle,unbracketed/react-intro-talk,thepauleh/slides,tairemad/fowa,f3r/spectacle,bestander/slings-and-arrows-of-NPM-installs,edge/reactdc-functional-flux,codemade/wmks-flux,kevinqualters/meetupslides,andrebeat/rust-presentation,andrebeat/rust-presentation,survivejs/react-for-awesome-people,codemade/wmks-react,vagmi/spectacle,hongkongjs/slides,tomduncalf/spectacle,tcoopman/spectacle,lowsky/spectacle,survivejs/react-for-awesome-people,leeric92/spectacle,FormidableLabs/spectacle,ivanoats/spectacle,waywaaard/spectacle,tikotzky/spectacle,hartmamt/builder-talk,slyg/async-js-prez,Crazy50/IsomorphicTalk,mabrasil/slides-nug_ce-2015,blefebvre/react-ottawajs-spectacle-deck,rektide/webpush-away-deck,waywaaard/spectacle,pedroha/spectacle,luisrudge/microservices-com-service-fabric,cateland/redux-presentation,luisrudge/microservices-com-service-fabric