chore(devDeps): rollback to Jest v21

jestjs/jest#5124

```
Object.defineProperty(location, "hostname", {
  value: "example.com",
  writable: true
});
```

```
TypeError: Cannot redefine property: hostname
        at Function.defineProperty (<anonymous>)
```

package.json

@@ -39,7 +39,7 @@
     "eslint-plugin-promise": "^3.6.0",
     "eslint-plugin-react": "^7.5.1",
     "husky": "^0.14.3",
-    "jest": "^22.0.1",
+    "jest": "^21.2.1",
     "lerna": "^2.5.1",
     "lint-staged": "^6.0.0",
     "prettier": "^1.9.2",