use mq to reduce font size for low resultions, max limit on width for slides set to 900px (closes #49)

Made the slideshow responsive

Include speaker notes plugin after reveal.js 

Must be called after reveal.js otherwise the Reveal object is undefined
and the plugin can't add it's event listener.

if you resized the window or visited the page on a small screen everything would be amiss

now, I've fixed that with a one-liner

Woohoo! The slideshow now responds to resizing of the browser nicely!