Alistair Johnston has explained how Celtic are aiming to be more ruthless this season and assert their dominance in Scottish football. The Celtic fullback was in a confident mood ahead of Kilmarnock’s visit to Parkhead this afternoon and was talking up how the team are feeling after getting the first season under Brendan Rodgers under their belts. The Canadian has just returned from a superb Copa America campaign and seems ready to hit the new Scottish Premiership season at full pelt and with this message, it seems like the Celtic fans could be in for a treat this season. Johnston warns Celtic…