Add uglify dependencies

Author: eKoopmans

package-lock.json

@@ -39,7 +39,8 @@
     "rimraf": "^2.6.2",
     "rollup": "^0.51.8",
     "rollup-plugin-commonjs": "^8.2.6",
-    "rollup-plugin-node-resolve": "^3.0.0"
+    "rollup-plugin-node-resolve": "^3.0.0",
+    "rollup-plugin-uglify": "^2.0.1"
   },
   "scripts": {
     "build": "rollup -c",