Update eslint requirement from ^1.10.3 to ^5.5.0

Updates the requirements on [eslint](https://github.com/eslint/eslint) to permit the latest version.
- [Release notes](https://github.com/eslint/eslint/releases)
- [Changelog](https://github.com/eslint/eslint/blob/master/CHANGELOG.md)
- [Commits](https://github.com/eslint/eslint/commits/v5.5.0)

Signed-off-by: dependabot[bot] <support@dependabot.com>

package.json

@@ -36,7 +36,7 @@
   },
   "devDependencies": {
     "clean-css": "^3.4.23",
-    "eslint": "^1.10.3",
+    "eslint": "^5.5.0",
     "graceful-fs": "^4.1.11",
     "mocha": "^3.2.0"
   }