chore(jest): add custom url to jest's testURL (#32)

Author: kristofdombi

package.json

@@ -52,6 +52,9 @@
     "react": "0.14.x || ^15.0.0 || ^16.0.0",
     "react-dom": "0.14.x || ^15.0.0 || ^16.0.0"
   },
+  "jest": {
+    "testURL": "http://localhost/"
+  },
   "devDependencies": {
     "babel-cli": "^6.24.1",
     "babel-eslint": "^7.2.3",