[package.json] 把 cross-env 从 devDependencies 迁移到 dependencies，因为在生产服务器上，由于内存不够或其他原因，仅仅 npm i --production 时，也需要 cross-env 来 npm run xxx.

package.json

@@ -18,6 +18,7 @@
     "commander": "^2.19.0",
     "compression": "^1.7.3",
     "cookie-parser": "^1.4.3",
+    "cross-env": "^5.1.3",
     "deepmerge": "^2.2.1",
     "errorhandler": "^1.5.0",
     "express": "^4.16.2",
@@ -47,7 +48,6 @@
     "babel-core": "7.0.0-bridge.0",
     "babel-jest": "^23.0.1",
     "babel-plugin-transform-imports": "^1.5.1",
-    "cross-env": "^5.1.3",
     "node-sass": "^4.9.0",
     "node-ssh": "^5.1.2",
     "sass-loader": "^7.0.1",