ch 8.1.1: add signin page, add sessions controller, add basic tests
ch 8.1.3
ch 8.2.4: working sign in, updated layout with Accounts menu, passing specs
ch 8.2.6 working sigin out, complete auth system
ch 8.3.1 install cucumber, run install generate
ch 8.3.3 cucumber tests, rspec custom matchers and helper
ch 8.5; finish cucumber, conclusion, exercises