* Drop support for ruby 2.3
* Docs: appraisal
* Drop support for rails <= 5.1
* Upgrade rubocop to 0.80
* Remove defunct code for EoL rails versions
* Rails 5+ style controller test params keyword
* Squash me
Co-Authored-By: Todd Lynam <TLynam@gmail.com>
Co-authored-by: Todd Lynam <TLynam@gmail.com>