title: Capybara-webkit with jruby
body: <p>I am working on moving our celerity based integration tests to capybara-webkit.
  The documentation provided on git-hub (https://github.com/thoughtbot/capybara-webkit) for capybara-webkit was helpful but i am unable to run my tests, ending up with error for jruby:</p>
  
  <p>NotImplementedError: fork is not available on this platform
  org/jruby/RubyKernel.java:1792:in `fork'</p>
  
  <p>Is there a way I can get capybara-webkit work with jruby?</p>