Fix typo on the master reference for the slack notifications
Fix typo on the master reference for the slack notifications

StackStorm/st2,Plexxi/st2,Plexxi/st2,nzlosh/st2,Plexxi/st2,nzlosh/st2,Plexxi/st2,StackStorm/st2,nzlosh/st2,nzlosh/st2,StackStorm/st2,StackStorm/st2