Bump eslint from 2.13.1 to 4.18.2

Bumps [eslint](https://github.com/eslint/eslint) from 2.13.1 to 4.18.2.
- [Release notes](https://github.com/eslint/eslint/releases)
- [Changelog](https://github.com/eslint/eslint/blob/master/CHANGELOG.md)
- [Commits](eslint/eslint@v2.13.1...v4.18.2)

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Author: dependabot[bot]