Upgrade slf4j 1.7.9, close #2457
Upgrade slf4j 1.7.9, close #2457

thkluge/gatling,pwielgolaski/gatling,gatling/gatling,MykolaB/gatling,timve/gatling,GabrielPlassard/gatling,gatling/gatling,wiacekm/gatling,gatling/gatling,wiacekm/gatling,wiacekm/gatling,gatling/gatling,thkluge/gatling,pwielgolaski/gatling,GabrielPlassard/gatling,ryez/gatling,thkluge/gatling,thkluge/gatling,MykolaB/gatling,ryez/gatling,wiacekm/gatling,timve/gatling,wiacekm/gatling,ryez/gatling,GabrielPlassard/gatling,pwielgolaski/gatling,MykolaB/gatling,timve/gatling,pwielgolaski/gatling,MykolaB/gatling,gatling/gatling,GabrielPlassard/gatling,timve/gatling,ryez/gatling