chore(package): update webpack-merge to version 3.0.0 (PatrickJS#1545)

https://greenkeeper.io/

Author: greenkeeperio-bot

package.json

@@ -149,7 +149,7 @@
  "webpack-dev-middleware": "^1.10.0",
  "webpack-dev-server": "2.4.1",
  "webpack-dll-bundles-plugin": "^1.0.0-beta.5",
- "webpack-merge": "~2.6.1"
+ "webpack-merge": "~3.0.0"
  },
  "repository": {
  "type": "git",