Real time member roles sync doesn't work for new users + patch

When a user first registers an account in drupal and the account ties up with a CiviCRM contact record, the membership data doesn't cause a Drupal role to be assigned. This is a problem if the method is set to 'real time' because the existing roles info will be missing.

This patch uses hook_user to get the roles to synchronise on account creation if 'real time' is in use.