book edits

[stedy]

Made some minor edits to your code, mostly to fix new ggplot2 and add in some libraries. Was thwarted by the twitter chapter because invariably there were some Inf values that hclust did not like.

[johnmyleswhite]

This looks amazing, Zach. We actually just made some changes that conflict with this, so we'll have to cherry-pick changes or do some reverting to make this work. We'll get to that after Strange Loop in a week.

[johnmyleswhite]

Hey Zach,

Any chance you've got a moment to see what happens if you run a git pull origin master? I've incorporated a lot of your changes, so it would be great to try to narrow down on those that are still needed.