chore(package): update standard to version 12.0.0

Closes #58

Author: greenkeeper[bot]

package.json

@@ -46,7 +46,7 @@
     "isparta": "^4.0.0",
     "mocha-junit-reporter": "^1.13.0",
     "run-sequence": "^1.2.2",
-    "standard": "^9.0.2",
+    "standard": "^12.0.0",
     "yargs": "^7.0.2"
   },
   "greenkeeper": {