chore(package): update prettier to version 2.0.4

Closes #41

Author: greenkeeper[bot]

package.json

@@ -38,7 +38,7 @@
     "husky": "^1.3.0",
     "jest": "^23.6.0",
     "lint-staged": "^8.1.0",
-    "prettier": "^1.15.3",
+    "prettier": "^2.0.4",
     "projectz": "^1.7.3",
     "semantic-release": "^15.1.4",
     "travis-deploy-once": "^5.0.11"