Added nextPath() to the controller and use it to step through posts.

chapter12-4
Use the nprogress package to make pagination nicer

chapter12-5
Use a single post subscription to ensure that we can always see the right post.

chapter12-6
Added basic upvoting algorithm.

chapter13-1
Grey out upvote link when not logged in / already voted.

chapter13-2
Added pluralize helper to format text better.

chapter13-3
Better upvoting algorithm.

chapter13-4
Added routes for post lists, and pages to display them.

chapter13-5
Added active classes to the header.

chapter13-6
Added post reordering animation.

chapter14-1
Fade items in when they are drawn.

chapter14-2