Update articles to consume the category attribute.
Modify the related categories partial to use real categories.
Modify the related links partial to use real categories and content.
Add an html processor for extracting the inner html of a node.
Add xpath targeting the intro paragraph.
Update the article decorator to be able to access article intro, and content without intro.
Update the article show template to the new design with related content.
Add Entity#== method.
Update features to check related content on article pages.
Update specs to check related content on article pages.
Move logic from controller to decorator.
Don't duplicate ArticleReader behaviour in test setup
Add fixes for IE8

Conflicts:
	app/assets/stylesheets/layout/page_specific/_article_page.scss
Merge branch 'article-related-content'