chore(package): update jest to version 20.0.2

Closes #7

Author: greenkeeper[bot]

package.json

@@ -29,7 +29,7 @@
     "enzyme": "^2.8.2",
     "extract-text-webpack-plugin": "2.1.0",
     "html-webpack-plugin": "2.28.0",
-    "jest": "^19.0.2",
+    "jest": "^20.0.2",
     "karma": "^1.6.0",
     "karma-chrome-launcher": "^2.0.0",
     "karma-typescript": "^3.0.0",