Headless Chrome driver for Capybara

Cuprite is a pure Ruby driver (read as no Java/Selenium/WebDriver/ChromeDriver requirement) for Capybara. It allows you to run your Capybara tests on a headless Chrome or Chromium browser while the latter is prefered for now because we work with tip-of-tree protocol.The emphasis was made on raw CDP protocol because Headless Chrome allows you to do so many cool things that are barely supported by WebDriver because it should have consistent design with other browsers. The design of the driver will be as close to Poltergeist as possible but it's not a goal.