chore(package): update jest to version 21.0.0

package.json

@@ -52,7 +52,7 @@
     "gh-pages": "github:rschamp/gh-pages#publish-branch-to-subfolder",
     "html-webpack-plugin": "^2.30.0",
     "immutable": "3.8.1",
-    "jest": "^20.0.4",
+    "jest": "^21.0.0",
     "lodash.bindall": "4.4.0",
     "lodash.debounce": "4.0.8",
     "lodash.defaultsdeep": "4.6.0",