Add custom cops to Chefstyle

[tas50]

There are many things we need to do project wide that are a lot easier to accomplish with rubocop cops. This copies of the scaffolding to do that from Cookstyle and add the shellout cop from cookstyle as well as a new cop.

Note: these are at refactor level so they don't fail builds

TODO: tests

Signed-off-by: Tim Smith tsmith@chef.io

[phiggins]

CI is unhappy:

rake aborted!
NameError: uninitialized constant RuboCop::Chef::CookbookHelpers
/workdir/lib/rubocop/cop/chef/ruby/ruby_27_keyword_argument_warnings.rb:36:in `<class:Ruby27KeywordArgumentWarnings>'
/workdir/lib/rubocop/cop/chef/ruby/ruby_27_keyword_argument_warnings.rb:35:in `<module:ChefRuby>'
/workdir/lib/rubocop/cop/chef/ruby/ruby_27_keyword_argument_warnings.rb:22:in `<module:Chef>'
/workdir/lib/rubocop/cop/chef/ruby/ruby_27_keyword_argument_warnings.rb:21:in `<module:Cop>'
/workdir/lib/rubocop/cop/chef/ruby/ruby_27_keyword_argument_warnings.rb:20:in `<module:RuboCop>'
/workdir/lib/rubocop/cop/chef/ruby/ruby_27_keyword_argument_warnings.rb:19:in `<top (required)>'
/workdir/lib/chefstyle.rb:37:in `require_relative'
/workdir/lib/chefstyle.rb:37:in `block in <top (required)>'
/workdir/lib/chefstyle.rb:34:in `glob'
/workdir/lib/chefstyle.rb:34:in `<top (required)>'
/workdir/Rakefile:23:in `require'
/workdir/Rakefile:23:in `<top (required)>'
/workdir/vendor/bundle/ruby/2.4.0/gems/rake-13.0.1/exe/rake:27:in `<top (required)>'
/usr/local/bin/bundle:30:in `block in <main>'
/usr/local/bin/bundle:22:in `<main>'
(See full trace by running task with --trace)

[phiggins]

Seems good to me 👍