ensure to depend on cross-env even if production

package.json

@@ -64,6 +64,7 @@
     "connect-flash": "~0.1.1",
     "connect-redis": "^3.3.0",
     "cookie-parser": "^1.4.3",
+    "cross-env": "^5.0.5",
     "crowi-pluginkit": "^1.1.0",
     "csrf": "~3.0.3",
     "css-loader": "^0.28.0",
@@ -130,7 +131,6 @@
     "cli": "~1.0.1",
     "colors": "^1.1.2",
     "commander": "^2.11.0",
-    "cross-env": "^5.0.5",
     "easy-livereload": "^1.2.0",
     "mocha": "^4.0.0",
     "morgan": "^1.8.2",