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

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended to check this file into your version control system.
 
-ActiveRecord::Schema.define(:version => 20110804225816) do
+ActiveRecord::Schema.define(:version => 20110805201426) do
 
   create_table "playlists", :force => true do |t|
     t.string   "name"
@@ -36,4 +36,11 @@ ActiveRecord::Schema.define(:version => 20110804225816) do
     t.string   "sha256"
   end
 
+  create_table "users", :force => true do |t|
+    t.string   "email"
+    t.string   "password"
+    t.datetime "created_at"
+    t.datetime "updated_at"
+  end
+
 end