Update autoprefixer-rails to 5.1.8.1
Update autoprefixer-rails to 5.1.8.1

orientation/orientation,smashingboxes/orientation,jefmathiot/orientation,jefmathiot/orientation,orientation/orientation,hashrocket/orientation,twinn/orientation,splicers/orientation,codeschool/orientation,LogicalBricks/orientation,ferdinandrosario/orientation,IZEA/orientation,robomc/orientation,cmckni3/orientation,liufffan/orientation,twinn/orientation,smashingboxes/orientation,friism/orientation,codeschool/orientation,hashrocket/orientation,friism/orientation,Scripted/orientation,orientation/orientation,codeschool/orientation,cmckni3/orientation,Scripted/orientation,splicers/orientation,robomc/orientation,liufffan/orientation,splicers/orientation,codio/orientation,codio/orientation,IZEA/orientation,orientation/orientation,ferdinandrosario/orientation,LogicalBricks/orientation,cmckni3/orientation,Scripted/orientation