Downgrade dependencies ⬇️

Author: lutien

package.json

@@ -26,7 +26,7 @@
     "eslint": "^3.6.0",
     "eslint-config-airbnb-base": "^11.1.1",
     "eslint-plugin-import": "^2.2.0",
-    "jest": "^20.0.0"
+    "jest": "^19.0.2"
   },
   "main": "./lib/index.js",
   "scripts": {