chore(package): update cross-env to version 7.0.1

Closes #37

Author: greenkeeper[bot]

package.json

@@ -72,7 +72,7 @@
     "babel-preset-stage-2": "^6.18.0",
     "babel-runtime": "^6.11.6",
     "coveralls": "^3.0.0",
-    "cross-env": "^5.0.0",
+    "cross-env": "^7.0.1",
     "jest": "^21.0.0",
     "nodemon": "^1.9.0",
     "npm-run-all": "^4.0.1",