Merge pull request #4 from kimjuny/greenkeeper/jest-21.0.0

Update jest to the latest version 🚀

Author: kimjuny

package.json

@@ -27,7 +27,7 @@
     "babel-preset-react": "^6.24.1",
     "babel-preset-stage-0": "^6.24.1",
     "codeclimate-test-reporter": "^0.5.0",
-    "jest": "^20.0.4",
+    "jest": "^21.0.0",
     "koa": "^2.3.0",
     "react": "^15.6.1",
     "react-dom": "^15.6.1",