Issue #002: Implements User model and makes a first attempt at the views and controllers.
Issue #001: Adds signin/signout links to navbar and an Account link when the user is logged in.  Issue #002: Adds User and Session controllers, models, and views.  As of this writing, the user can at least create an account, sign in, sign out, edit his or her contact information and password, and view the page that will eventually contain the list of courses being tracked.  Issue #006: Technically implements the functionality of the Course and Tracking models, though without actual data this has not been tested.
Resolves merging issues.