Merge pull request #11 from ShayanZafar/gh-pages

Structure and Content changes
add tech graphic
Merge pull request #13 from jbraffoul/add-tech-graphic

add tech graphic
center webvtt over video
Merge pull request #14 from jbraffoul/center-webvtt-text

center webvtt over video
remove misplaced tag
add margin-bottom to ul
Merge pull request #15 from jbraffoul/gh-pages-dev

minor css fix + remove misplaced tag
added mozilla image
Merge branch 'gh-pages' of https://github.com/jbraffoul/webvtt-presentation into gh-pages
update
added new slide: optiona webvtt file stuff and an image for the main page which probably needs to be adjusted