chore(package): update prettier to version 1.18.0

Closes #73

Author: greenkeeper[bot]

package.json

@@ -90,7 +90,7 @@
     "lint-staged": "8.1.0",
     "mocha": "5.2.0",
     "nodemon": "1.18.7",
-    "prettier": "1.15.2",
+    "prettier": "1.18.0",
     "rimraf": "2.6.2",
     "tslint": "5.11.0",
     "tslint-config-prettier": "1.17.0",