Update prettier to version 1.12.0 (#206)

Author: greenkeeper[bot]

Diff for: package.json

@@ -38,7 +38,7 @@
     "eslint-config-problems": "0.0.2",
     "nyc": "^11.0.2",
     "postcss-import": "^11.0.0",
-    "prettier": "1.11.0",
+    "prettier": "1.12.0",
     "sugarss": "^1.0.0",
     "uuid": "^3.0.1"
   },