Sign In: Part III
 Changes to be committed:
	modified:   app/controllers/users_controller.rb
	modified:   app/helpers/application_helper.rb
	modified:   app/views/layouts/_header.html.erb
	modified:   log/development.log
	modified:   log/test.log
	modified:   spec/features/create_user_spec.rb
	modified:   spec/features/sign_in_spec.rb