RuboCop cleanup
Switch to installing release version of Berkshelf
Add Gemfile with set of test mechanisms etc.
Ensure Berksfile & Berksfile.lock ship to Chef Server
Refactor Guardfile to use guard-kitchen & other goodies
Convert to Berkshelf 3 format, pin git to specific refs for sanity
Add sensible RuboCop config
Use Jenkins cookbook ~> 2.1 from community site
Drop Debian support
Fix BATS test for Berkshelf
Clean up & simplify Test Kitchen config
Drop manual, rbenv-powered Chef etc. in favor of Chef DK