silos and stuff
organizes sections
adds some Sass
adds Yeoman images
adds previous
Merge branch 'silo-buster' of https://github.com/rabellamy/yeoman-demo into YP-01

Conflicts:
	index.html
YP-01 - Added to the end of the presentation
YP-01 - Added just a few more slides and a link back to how to create generators for Yeoman.