Save changes to user objects in a backwards compatible way.

According to drumm, Drupal 7 hasn't fully moved away from
using user_save()'s $edit parameter. Switch to the 'old'
way of saving changes to the user object, so that modules
such as Bakery don't break.

Signed-off-by: Nigel Cunningham <nigel@nigelcunningham.com.au>