fix(package): update gulp-wrap to version 0.15.0

Closes #278

Author: greenkeeper[bot]

package.json

@@ -64,7 +64,7 @@
     "gulp-stylus": "^2.7.0",
     "gulp-uglify": "^1.5.4",
     "gulp-watch": "^4.3.5",
-    "gulp-wrap": "^0.13.0",
+    "gulp-wrap": "^0.15.0",
     "gulp.spritesmith": "^6.9.0",
     "handlebars": "^4.0.11",
     "inquirer": "^4.0.0",