message: fix dev dependencies
diff: "coveralls": "2.11.16",
  "cross-env": "3.1.4",
  "css-loader": "0.26.2",
  - "extract-text-webpack-plugin": "2.0.0",
  + "extract-text-webpack-plugin": "2.0.0-beta.4",
  "file-loader": "0.10.0",
  "handlebars-loader": "1.4.0",
  "html-loader": "0.4.5",
  