Update meta files: README, .gemspec, LICENSE, CONTRIBUTING
Rakefile - leave only Bundler / gem tasks
Remove legacy Rails plugin code
Add .gitignore to the repo
Add a Gemfile to the repo
Remove legacy (Dradis 2.x) libraries
Add RSpec as a dev dependency
Connect Engine with Dradis (controller, routes)
Provide basic Dradis 3.x plugin skeleton
Require the 'csv' from stdlib
Implement export to CSV action