chore(package): update tslint to version 5.9.1

Closes #5

Author: greenkeeper[bot]

package.json

@@ -54,7 +54,7 @@
     "protractor": "~5.1.2",
     "semantic-release": "^6.3.6",
     "ts-node": "~3.3.0",
-    "tslint": "~5.5.0",
+    "tslint": "~5.9.1",
     "typescript": "~2.4.1"
   },
   "repository": {