Changed the target location of the nav link to go to the root directory and scroll down to the user stories section
Added Angular's anchor scrolling function to the Directory module
Added an empty #user_stories_section div to the end of How It Works list so that the page will scroll down when the User Stories link is clicked
Merge pull request #565 from shindostrz/master

Added Angular's anchorScroll function and changed the nav link for User Stories