Add authentication and User model

* Add User model
* Add SessionsController
* Add password authentication on User
* Request authentication for all actions except sign in
* Add some helpers for ApplicationController
* Update features to work with mandatory authentication

config/routes.rb

@@ -1,4 +1,6 @@
 Scube::Application.routes.draw do
+  resources :sessions, :only => [:new, :create]
+
   resources :tracks do
     get 'stream', :on => :member
   end