Add Sessions controller, routes and test for basic sign in page.
Add tests for sign-in page, create form for sign in page and define create method to render 'new' view for checking debug output - page parameters.
Implement sign in - add remember token saved as cookie and encrypted in the database, change header to include drop down menu and use session helper in its controller (and not only view).
Implement automatic sign in for registered users and sign out (for all).
Finish sign in - replace form_for with form_tag according to exercise (i chose not to decouple test from implementation - exercise 2).
Add basic cucumber test and use RSpec custom matcher and helper.