home page and login page

users click on login button before being redirected to github for oauth
Merge pull request #22 from lighthouse-labs/feature/44-student-login-flow

home page and login page
Merge branch 'master' into feature/45-users-sti

Conflicts:
	app/controllers/application_controller.rb
	app/controllers/sessions_controller.rb
	spec/controllers/sessions_controller_spec.rb
	spec/features/authentication_spec.rb