chore(package): update eslint-config-airbnb-base to version 12.1.0

Closes #57

Author: greenkeeper[bot]

package.json

@@ -42,7 +42,7 @@
     "babel-preset-es2015": "^6.18.0",
     "chai": "^3.5.0",
     "eslint": "^3.10.2",
-    "eslint-config-airbnb-base": "^11.1.2",
+    "eslint-config-airbnb-base": "^12.1.0",
     "eslint-plugin-import": "^2.2.0",
     "mocha": "^3.2.0"
   }