package.json: add cross-env

package.json

@@ -17,7 +17,7 @@
     "deploy": "npm run build:file && cooking build -c build/cooking.demo.js -p && echo element.eleme.io>>examples/element-ui/CNAME && gh-pages -d examples/element-ui --remote eleme && del examples/element-ui",
     "pub": "sh build/release.sh",
     "pub:all": "npm run dist:all && lerna publish",
-    "build:utils": "BABEL_ENV=utils babel src --out-dir lib --ignore src/index.js",
+    "build:utils": "cross-env BABEL_ENV=utils babel src --out-dir lib --ignore src/index.js",
     "clean": "rimraf lib && rimraf packages/*/lib && rimraf test/**/coverage",
     "lint": "eslint src/**/* test/**/* packages/**/*.{js,vue} build/**/* --quiet",
     "test:watch": "karma start test/unit/karma.conf.js",
@@ -61,6 +61,7 @@
     "cooking-vue2": "^0.1.4",
     "coveralls": "^2.11.14",
     "cp-cli": "^1.0.2",
+    "cross-env": "^3.1.3",
     "css-loader": "^0.24.0",
     "es6-promise": "^4.0.5",
     "extract-text-webpack-plugin": "^1.0.1",