Set custom headers using Capybara-Mechanize

Capybara-Mechanize

When /^I go to google$/ do
  p page.driver.agent.request_headers = {'Accept-Language' => 'en-gb'} 
  visit('http://localhost:7001')
end

Then /^I should see the title google$/ do
  find('title').text.should == 'RubyGems Documentation Index'
end