Bumps [eslint](https://github.com/eslint/eslint) from 4.13.1 to 4.15.0.
- [Release notes](https://github.com/eslint/eslint/releases)
- [Changelog](https://github.com/eslint/eslint/blob/master/CHANGELOG.md)
- [Commits](https://github.com/eslint/eslint/compare/v4.13.1...v4.15.0)