button cancel, set icon with before

src/Bundle/ChillMainBundle/Resources/public/vuejs/_components/OnTheFly.vue

@@ -91,11 +91,11 @@ export default {
       classAction() {
          switch (this.action) {
             case 'show':
-               return 'bt-show';
+               return 'btn-show';
             case 'edit':
-               return 'bt-update';
+               return 'btn-update';
             case 'create':
-               return 'bt-create';
+               return 'btn-create';
          }
       },
       titleAction() {