chore(package): update jest to version 21.0.1 (#33)

* chore(package): update jest to version 21.0.1

Closes #32

* generated yarn.lock

Author: chrishelgert

package.json

@@ -44,7 +44,7 @@
     "babel-preset-es2015": "^6.18.0",
     "babel-preset-react": "^6.16.0",
     "cross-env": "^5.0.0",
-    "jest": "^20.0.0",
+    "jest": "^21.0.1",
     "prop-types": "^15.5.10",
     "react": "^15.4.1",
     "react-test-renderer": "^15.4.1",