use the github repo instead of amazon link
add the post by Kieran Healy
add sharelatex.com
move some applications to the website category
document fig.retina
a post from THE ROSTRUM
two more posts
link to the gist of knitr vignettes
document the collapse option
typo: strip.white instead of stripe.white
three book reviews and another blog post
the default of fig.retina is 1 now
the new strip.white option