move sessions outside of the cache directory

Author: fabpot

app/config/config.yml

@@ -28,6 +28,7 @@ framework:
     session:
         # handler_id set to null will use default session handler from php.ini
         handler_id:  ~
+        save_path:   %kernel.root_dir%/../var/sessions/%kernel.environment%
     fragments:       ~
     http_method_override: true
     assets: ~