chore(package): update jest to version 21.0.0

Author: greenkeeper[bot]

package.json

@@ -53,7 +53,7 @@
     "file-loader": "1.0.0",
     "html-webpack-plugin": "2.30.0",
     "husky": "0.14.3",
-    "jest": "20.0.4",
+    "jest": "21.0.0",
     "node-sass": "4.5.3",
     "open-browser-webpack-plugin": "0.0.5",
     "react-addons-test-utils": "15.6.0",