Fix click_link fails with Capybara >= 0.4.0

w/ assist from @botandrose

Should be working correctly on Capybara 0.3.9 as well.
Conflicts:

	lib/cucumber/rails/capybara_javascript_emulation.rb
Fix capybara rack/test

Conflicts:

	lib/cucumber/rails/capybara/javascript_emulation.rb
Update gemspec
Merge pull request #242 from Vanuan/cucumber-rails2_v0.3.3

Cucumber rails2 v0.3.3