STEPHEN COLLINS Political EditorBERTIE AHERN, Gerry Adams and Martin McGuinness have emerged as Tony Blair’s favourite Irish politicians.In his autobiography, A Journey, published yesterday, he reveals how he made contact with Sinn Féin and with Mr Ahern before he achieved power in May, 1997.“I met Bertie Ahern, also a leader of the Opposition, and we got on immediately like the proverbial house o