build(package): update webpack, -uglifyjs-webpack-plugin

Workaround for uglifyjs-webpack-plugin is no longer required webpack-contrib/uglifyjs-webpack-plugin#241 (comment)

Author: gr2m

package.json

@@ -70,8 +70,7 @@
     "standard-markdown": "^4.0.2",
     "string-to-arraybuffer": "^1.0.0",
     "typescript": "^2.6.2",
-    "uglifyjs-webpack-plugin": "1.2.0",
-    "webpack": "^4.0.0-beta.1",
+    "webpack": "^4.0.0-beta.2",
     "webpack-bundle-analyzer": "^2.10.0",
     "webpack-cli": "^2.0.4"
   },