Tooling updates (adamgruber#328)

* pkg: add prettier, husky, lint-staged

* pkg: upgrade eslint

* pkg: configure eslint

* pkg: configure prettier

* lint: fix errors

* src: format with prettier

* test: format with prettier

* pkg: remove unused eslint dev deps

* pkg: update mocha

* pkg: update misc dev deps

* ci: remove travis config

* Update changelog

Author: adamgruber