chore(package): update ts-jest to version 20.0.3

Closes #23

Author: greenkeeper[bot]

package.json

@@ -24,7 +24,7 @@
     "lerna": "2.0.0-rc.1",
     "react-addons-test-utils": "^15.4.2",
     "react-test-renderer": "^15.4.2",
-    "ts-jest": "^19.0.3",
+    "ts-jest": "^20.0.3",
     "tslint": "^5.0.0",
     "typescript": "^2.2.1"
   },