chore(package): update eslint to version 5.12.1

Closes #65

Author: greenkeeper[bot]

package.json

@@ -35,7 +35,7 @@
     "babel-plugin-transform-async-to-generator": "^6.0.14",
     "babel-preset-es2015-node5": "^1.1.0",
     "codeclimate-test-reporter": "^0.4.0",
-    "eslint": "^4.1.0",
+    "eslint": "^5.12.1",
     "istanbul": "^1.0.0-alpha.2",
     "jison": "^0.4.15",
     "mocha": "^4.0.1",