chore(package): update cross-env to version 5.1.2

Closes #6

Author: greenkeeper[bot]

package.json

@@ -37,7 +37,7 @@
     "chalk": "1.1.3",
     "cheerio": "0.22.0",
     "compression": "1.6.2",
-    "cross-env": "4.0.0",
+    "cross-env": "5.1.2",
     "css-loader": "^0.28.0",
     "eslint": "^3.19.0",
     "eslint-plugin-import": "^2.2.0",