update math example to use 4.0 plugin syntax
update math example to use 4.0 plugin syntax

lvh/reveal.js,siddhartha-gadgil/presentations,kenkunz/js-crash-course,dbs/reveal.js,rbtcollins/reveal.js,tehfedaykin/10CommandmentsofCommunityOrganizing,lvh/reveal.js,dbs/reveal.js,hakimel/reveal.js,Jean85/reveal.js,jayramj/agile-retro,rbtcollins/reveal.js,maximesinclair/presentations,kenkunz/js-crash-course,siddhartha-gadgil/presentations,tehfedaykin/10CommandmentsofCommunityOrganizing,seefood/DIYHolidays,Jean85/reveal.js,rbtcollins/reveal.js,seefood/DIYHolidays,siddhartha-gadgil/presentations,maximesinclair/presentations,rbtcollins/reveal.js,10xEngineer/reveal.js,rbtcollins/reveal.js,jayramj/agile-retro,10xEngineer/reveal.js,rbtcollins/reveal.js,hakimel/reveal.js