(Adds details) By Mike Collett LONDON, Oct 9 (Reuters) – Sam Allardyce was appointed as Premier League Sunderland’s new manager on Friday, eight years after he had a brief spell in charge of their arch-rivals Newcastle United. Sunderland confirmed the appointment in a statement on their website (www.safc.com), less than a week after Dutchman Dick Advocaat left the club on Sunday. Sunderland are currently 19th in the Premier League, …