capybara mechanize headers
# capybara '1.1.2
require 'capybara'
require 'capybara/dsl'
require 'capybara/mechanize'
Capybara.default_driver = :mechanize
Capybara.app_host = 'http://httpbin.org'
include Capybara::DSL
Capybara.current_session.driver.browser.agent.set_proxy ('www-cache.reith.bbc.co.uk', 80)
Capybara.current_session.driver.browser.agent.request_headers = {"X-Header" => "value"}
visit '/headers'
puts page.find('p').text