chore(package): update standard to version 7.1.0

https://greenkeeper.io/

Author: greenkeeperio-bot

package.json

@@ -32,6 +32,6 @@
     "mocha": "^2.3.4",
     "nyc": "^6.4.2",
     "rimraf": "^2.5.0",
-    "standard": "^5.4.1"
+    "standard": "^7.1.0"
   }
 }