Implement user sign out (destroy current session)

app/controllers/sessions_controller.rb

@@ -11,4 +11,9 @@ class SessionsController < ApplicationController
       render 'new'
     end
   end
+
+  def destroy
+    reset_session
+    redirect_to :root
+  end
 end

app/views/layouts/application.html.haml

@@ -13,5 +13,7 @@
             = link_to 'Scube', root_path
           %li
             = link_to 'Playlists', playlists_path
+          %li
+            = link_to 'Sign out', signout_path
 
     = yield