chore(package): update uglifyjs-webpack-plugin to version 2.0.1

Closes #14

Author: greenkeeper[bot]

package.json

@@ -46,7 +46,7 @@
     "jest-cli": "^21.2.1",
     "react": "^16.0.0",
     "react-dom": "^16.0.0",
-    "uglifyjs-webpack-plugin": "^1.0.1",
+    "uglifyjs-webpack-plugin": "^2.0.1",
     "webpack": "^3.8.1"
   },
   "dependencies": {