Update eslint to version 5.0.0 (#47)

Author: greenkeeper[bot]

package.json

@@ -35,7 +35,7 @@
     "through2": "^2.0.0"
   },
   "devDependencies": {
-    "eslint": "^4.0.0",
+    "eslint": "^5.0.0",
     "eslint-config-lesshint": "^1.0.3",
     "mocha": "^5.0.0",
     "sinon": "^6.0.0",