added has_valid_password and routes for users and sessions
added sessions controller
added current_user to application_controller
created users controller
added new and create methods to users_controller
created new session view
added view for users#new
added login/logout to nav temporarily
added welcome controller and page for temporary homepage and testing
added root to routes
added bcrypt to gemfile for password encryption
Merge pull request #1 from ballauriena/login

Looks good.  Thanks for knocking that out!