chore(package): update jest to version 20.0.2

Closes #4

Author: greenkeeper[bot]

package.json

@@ -35,7 +35,7 @@
   "devDependencies": {
     "eslint": "^3.19.0",
     "eslint-config-stylelint": "^6.0.0",
-    "jest": "^19.0.2",
+    "jest": "^20.0.2",
     "stylelint": "^7.10.1"
   },
   "peerDependencies": {