chore(package): update jest to version 21.0.1

Closes #42

Author: greenkeeper[bot]

package.json

@@ -26,7 +26,7 @@
     "cross-spawn": "^5.1.0",
     "enzyme": "^2.9.1",
     "express": "^4.15.3",
-    "jest": "^20.0.4",
+    "jest": "^21.0.1",
     "mocha": "^3.4.2",
     "peer-tester": "^1.0.6",
     "react": "^15.6.1",