Added prefix for webkit browsers

Author: Bogdan Androsov

dist/rzslider.js

@@ -990,6 +990,7 @@
           var tick = {
             selected: self.isTickSelected(value),
             style: {
+              webkitTransform: translate + '(' + Math.round(position) + 'px)',
               transform: translate + '(' + Math.round(position) + 'px)'
             }
           };

src/rzslider.js

@@ -994,6 +994,7 @@
           var tick = {
             selected: self.isTickSelected(value),
             style: {
+              webkitTransform: translate + '(' + Math.round(position) + 'px)',
               transform: translate + '(' + Math.round(position) + 'px)'
             }
           };