Rename ArraySessionStorage to make it clear the session is a mock for testing purposes only.
Has BC class for ArraySessionStorage
Added sanity check when starting the session.
Fixed typos and incorrect php extension test method
session_module_name() also sets session.save_handler, so must use extension_loaded() to check if module exist
or not.
Respect autostart settings.
Session object now implements SessionInterface to make it more portable.
AbstractSessionStorage and SessionSaveHandlerInterface now makes implementation
of session storage drivers simple and easy to write for both custom save handlers
and native php save handlers and respect the PHP session workflow.