Add ESLint 5 support (#240)

Author: Alex-Sokolov

package.json

@@ -16,7 +16,7 @@
     "index.js"
   ],
   "peerDependencies": {
-    "eslint": ">=1.6.0 <5.0.0",
+    "eslint": ">=1.6.0 <6.0.0",
     "webpack": ">=2.0.0 <5.0.0"
   },
   "dependencies": {
@@ -28,7 +28,7 @@
   },
   "devDependencies": {
     "ava": "^0.17.0",
-    "eslint": "^4.0.0",
+    "eslint": "^5.1.0",
     "eslint-friendly-formatter": "^2.0.4",
     "npmpub": "^3.0.1",
     "webpack": "^4.0.0"