chore(package): update jest to version 21.0.0

* chore(package): update lockfile

https://npm.im/greenkeeper-lockfile

Author: greenkeeper[bot]

package.json

@@ -44,7 +44,7 @@
     "eslint-plugin-jest": "^21.0.0",
     "git-exec-and-restage": "^1.0.1",
     "husky": "^0.14.3",
-    "jest": "^20.0.4",
+    "jest": "^21.0.0",
     "lint-staged": "^4.0.4",
     "netlify-cms": "^0.5.0-beta.1",
     "nuxt": "^1.0.0-rc8",