chore(package): update gulp-uglify to version 2.0.0 (#1086)

https://greenkeeper.io/

Author: greenkeeperio-bot

package.json

@@ -46,7 +46,7 @@
     "gulp-sass-lint": "~1.2.0",
     "gulp-size": "~2.1.0",
     "gulp-sourcemaps": "~1.6.0",
-    "gulp-uglify": "~1.5.4",
+    "gulp-uglify": "~2.0.0",
     "gulp-useref": "~3.1.0",
     "gulp-util": "~3.0.7",
     "gulp-watch": "~4.3.8",