chore(package): update prettier to version 2.0.0

Closes #73

Author: greenkeeper[bot]

package.json

@@ -91,7 +91,7 @@
     "lint-staged": "8.1.0",
     "mocha": "5.2.0",
     "nodemon": "1.18.7",
-    "prettier": "1.15.2",
+    "prettier": "2.0.0",
     "rimraf": "2.6.2",
     "ts-node": "^7.0.1",
     "tslint": "5.11.0",